A.18 Containers
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This clause presents the specifications of the package Containers and several child packages, which provide facilities for storing collections of elements.
A variety of sequence and associative containers are provided. Each container package defines a cursor type as well as a container type. A cursor is a reference to an element within a container. Many operations on cursors are common to all of the containers. A cursor referencing an element in a container is considered to be overlapping only with the element itself.
Some operations of the language-defined child units of Ada.Containers have access-to-subprogram parameters. To ensure such operations are well-defined, they guard against certain actions by the designated subprogram. An action on a container that can add or remove an element is considered to tamper with cursors, and these are prohibited during all such operations. An action on a container that can replace an element with one of a different size is considered to tamper with elements, and these are prohibited during certain of such operations. The details of the specific actions that are considered to tamper with cursors or elements are defined for each child unit of Ada.Containers.
Several of the language-defined child units of Ada.Containers include a nested package named Stable, which provides a view of a container that prohibits any operations that would tamper with elements. By using a Stable view for manipulating a container, the number of tampering checks performed while performing the operations can be reduced. The details of the Stable subpackage are defined separately for each child unit of Ada.Containers that includes such a nested package.
Within this clause we provide O(X). Presuming f is some function of a length parameter N and t(N) is the time the operation takes (on average or worst case, as specified) for the length N, a complexity of O(f(N)) means that there exists a finite A such that for any N, t(N)/f(N) < A.
If the advice suggests that the complexity should be less than O(f(N)), then for any arbitrarily small positive real D, there should exist a positive integer M such that for all N > M, t(N)/f(N) < D.
When a formal function is used to provide an ordering for a container, it is generally required to define a strict weak ordering. A function "<" defines a strict weak ordering if it is irreflexive, asymmetric, transitive, and in addition, if x < y for any values x and y, then for all other values z, (x < z) or (z < y). Elements are in a smallest first order using such an operator if, for every element y with a predecessor x in the order, (y < x) is false.
Language Design Principles
- (Expandable) Vectors of any nonlimited type;
- Doubly-linked Lists of any nonlimited type;
- Hashed Maps keyed by any nonlimited hashable type, and containing any nonlimited type;
- Ordered Maps keyed by any nonlimited ordered type, and containing any nonlimited type;
- Hashed Sets of any nonlimited hashable type;
- Ordered Sets of any nonlimited ordered type;
- Multiway Trees of any nonlimited type;
- Holders of any (indefinite) nonlimited type;
- Synchronized queues of any definite nonlimited type; and
- Priority queues of any definite nonlimited type.
- Library packages must allow concurrent calls – multiple tasks can use the packages as long as they operate on separate containers. Thus, it is only necessary for a user to protect a container if a single container needs to be used by multiple tasks and concurrent calls to operations of the container have overlapping parameters.
- Language-defined types must stream "properly". That means that the stream attributes can be used to implement persistence of containers when necessary, and containers can be passed between partitions of a program.
- Equality of language-defined types must compose “properly”. This means that the version of "=" directly used by users is the same one that will be used in generics and in predefined equality operators of types with components of the containers and/or cursors. This prevents the abstraction from breaking unexpectedly.
- Redispatching is not allowed (unless it is required). That means that overriding a container operation will not change the behavior of any other predefined container operation. This provides a stable base for extensions.
Static Semantics
7/4Certain subprograms declared within instances of some of the generic packages presented in this clause are said to perform indefinite insertion. These subprograms are those corresponding (in the sense of the copying described in subclause 12.3) to subprograms that have formal parameters of a generic formal indefinite type and that are identified as performing indefinite insertion in the subclause defining the generic package.
If a subprogram performs indefinite insertion, then certain run-time checks are performed as part of a call to the subprogram; if any of these checks fail, then the resulting exception is propagated to the caller and the container is not modified by the call. These checks are performed for each parameter corresponding (in the sense of the copying described in 12.3) to a parameter in the corresponding generic whose type is a generic formal indefinite type. The checks performed for a given parameter are those checks explicitly specified in subclause 4.8 that would be performed as part of the evaluation of an initialized allocator whose access type is declared immediately within the instance, where:
- the value of the
qualified_expressionis that of the parameter; and 10/4 - the designated subtype of the access type is the subtype of the parameter; and
- finalization of the collection of the access type has started if and only if the finalization of the instance has started.
Implementation Requirements
12/5For an indefinite container (one whose type is defined in an instance of a child package of Containers whose defining_identifier contains "Indefinite"), each element of the container shall be created when it is inserted into the container and finalized when it is deleted from the container (or when the container object is finalized if the element has not been deleted). For a bounded container (one whose type is defined in an instance of a child package of Containers whose defining_identifier starts with "Bounded") that is not an indefinite container, all of the elements of the capacity of the container shall be created and default initialized when the container object is created; the elements shall be finalized when the container object is finalized. [For other kinds of containers, when elements are created and finalized is unspecified.]
For an instance I of a container package with a container type, the specific type T of the object returned from a function that returns an object of an iterator interface, as well as the primitive operations of T, shall be nonblocking. The Global aspect specified for T and the primitive operations of T shall be (in all, out synchronized) or a specification that allows access to fewer global objects.
Extensions to Ada 95
Wording Changes from Ada 2005
Extensions to Ada 2012
Wording Changes from Ada 2012
A.18.1 The Package Containers
1/2The package Containers is the root of the containers subsystem.
Static Semantics
2/2The library package Containers has the following declaration:
package Ada.Containers
with Pure is
4/2type Hash_Type is mod implementation-defined;
5/2type Count_Type is range 0 .. implementation-defined;
5.1/3Capacity_Error : exception;
6/2end Ada.Containers;
Hash_Type represents the range of the result of a hash function. Count_Type represents the (potential or actual) number of elements of a container.
Capacity_Error is raised when the capacity of a container is exceeded.
Implementation Advice
8/2Hash_Type'Modulus should be at least 2**32. Count_Type'Last should be at least 2**31–1.
Extensions to Ada 95
Incompatibilities With Ada 2005
use_clause, and an entity with the name Capacity_Error is defined in a package that is also referenced in a use_clause, the entity Capacity_Error may no longer be use-visible, resulting in errors. This should be rare and is easily fixed if it does occur. A.18.2 The Generic Package Containers.Vectors
1/2The language-defined generic package Containers.Vectors provides private types Vector and Cursor, and a set of operations for each type. A vector container allows insertion and deletion at any position, but it is specifically optimized for insertion and deletion at the high end (the end with the higher index) of the container. A vector container also provides random access to its elements.
A vector container behaves conceptually as an array that expands as necessary as items are inserted. The length of a vector is the number of elements that the vector contains. The capacity of a vector is the maximum number of elements that can be inserted into the vector prior to it being automatically expanded.
Elements in a vector container can be referred to by an index value of a generic formal type. The first element of a vector always has its index value equal to the lower bound of the formal type.
A vector container may contain empty elements. Empty elements do not have a specified value.
Static Semantics
5/2The generic library package Containers.Vectors has the following declaration:
with Ada.Iterator_Interfaces;
generic
type Index_Type is range <>;
type Element_Type is private;
with function "=" (Left, Right : Element_Type)
return Boolean is <>;
package Ada.Containers.Vectors
with Preelaborate, Remote_Types,
Nonblocking, Global => in out synchronized is
subtype Extended_Index is
Index_Type'Base range
Index_Type'First-1 ..
Index_Type'Min (Index_Type'Base'Last - 1, Index_Type'Last) + 1;
No_Index : constant Extended_Index := Extended_Index'First;
type Vector is tagged private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Iterator_View => Stable.Vector,
Aggregate => (Empty => Empty,
Add_Unnamed => Append,
New_Indexed => New_Vector,
Assign_Indexed => Replace_Element),
Stable_Properties => (Length, Capacity,
Tampering_With_Cursors_Prohibited,
Tampering_With_Elements_Prohibited),
Default_Initial_Condition =>
Length (Vector) = 0 and then
(not Tampering_With_Cursors_Prohibited (Vector)) and then
(not Tampering_With_Elements_Prohibited (Vector)),
Preelaborable_Initialization ;
9/5type Cursor is private
with Preelaborable_Initialization ;
10/2Empty_Vector : constant Vector;
11/2No_Element : constant Cursor;
11.1/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
function Has_Element (Container : Vector; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
package Vector_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
12/2function "=" (Left, Right : Vector) return Boolean;
12.1/5function Tampering_With_Cursors_Prohibited
(Container : Vector) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
12.2/5function Tampering_With_Elements_Prohibited
(Container : Vector) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
12.3/5function Maximum_Length return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
12.4/5function Empty (Capacity : Count_Type := implementation-defined)
return Vector
with Pre => Capacity <= Maximum_Length
or else raise Constraint_Error,
Post =>
Capacity (Empty'Result) >= Capacity and then
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
13/5function To_Vector (Length : Count_Type) return Vector
with Pre => Length <= Maximum_Length or else raise Constraint_Error,
Post =>
To_Vector'Result.Length = Length and then
not Tampering_With_Elements_Prohibited (To_Vector'Result)
and then
not Tampering_With_Cursors_Prohibited (To_Vector'Result)
and then
To_Vector'Result.Capacity >= Length;
14/5function To_Vector
(New_Item : Element_Type;
Length : Count_Type) return Vector
with Pre => Length <= Maximum_Length or else raise Constraint_Error,
Post =>
To_Vector'Result.Length = Length and then
not Tampering_With_Elements_Prohibited (To_Vector'Result)
and then
not Tampering_With_Cursors_Prohibited (To_Vector'Result)
and then
To_Vector'Result.Capacity >= Length;
14.1/5function New_Vector (First, Last : Index_Type) return Vector is
(To_Vector (Count_Type (Last - First + 1)))
with Pre => First = Index_Type'First;
15/5function "&" (Left, Right : Vector) return Vector
with Pre => Length (Left) <= Maximum_Length - Length (Right)
or else raise Constraint_Error,
Post => Length (Vectors."&"'Result) =
Length (Left) + Length (Right) and then
not Tampering_With_Elements_Prohibited
(Vectors."&"'Result) and then
not Tampering_With_Cursors_Prohibited
(Vectors."&"'Result) and then
Vectors."&"'Result.Capacity >=
Length (Left) + Length (Right);
16/5function "&" (Left : Vector;
Right : Element_Type) return Vector
with Pre => Length (Left) <= Maximum_Length - 1
or else raise Constraint_Error,
Post => Vectors."&"'Result.Length = Length (Left) + 1 and then
not Tampering_With_Elements_Prohibited
(Vectors."&"'Result) and then
not Tampering_With_Cursors_Prohibited
(Vectors."&"'Result) and then
Vectors."&"'Result.Capacity >= Length (Left) + 1;
17/5function "&" (Left : Element_Type;
Right : Vector) return Vector
with Pre => Length (Right) <= Maximum_Length - 1
or else raise Constraint_Error,
Post => Length (Vectors."&"'Result) = Length (Right) + 1 and then
not Tampering_With_Elements_Prohibited
(Vectors."&"'Result) and then
not Tampering_With_Cursors_Prohibited
(Vectors."&"'Result) and then
Vectors."&"'Result.Capacity >= Length (Right) + 1;
18/5function "&" (Left, Right : Element_Type) return Vector
with Pre => Maximum_Length >= 2 or else raise Constraint_Error,
Post => Length ("&"'Result) = 2 and then
not Tampering_With_Elements_Prohibited
(Vectors."&"'Result) and then
not Tampering_With_Cursors_Prohibited
(Vectors."&"'Result) and then
Vectors."&"'Result.Capacity >= 2;
19/5function Capacity (Container : Vector) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
20/5procedure Reserve_Capacity (Container : in out Vector;
Capacity : in Count_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Container.Capacity >= Capacity;
21/5function Length (Container : Vector) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
22/5procedure Set_Length (Container : in out Vector;
Length : in Count_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length <= Maximum_Length
or else raise Constraint_Error),
Post => Container.Length = Length and then
Capacity (Container) >= Length;
23/5function Is_Empty (Container : Vector) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Length (Container) = 0);
24/5procedure Clear (Container : in out Vector)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = 0;
25/5function To_Cursor (Container : Vector;
Index : Extended_Index) return Cursor
with Post => (if Index in
First_Index (Container) .. Last_Index (Container)
then Has_Element (Container, To_Cursor'Result)
else To_Cursor'Result = No_Element),
Nonblocking, Global => null, Use_Formal => null;
26/5function To_Index (Position : Cursor) return Extended_Index
with Nonblocking, Global => in all;
26.1/5function To_Index (Container : Vector;
Position : Cursor) return Extended_Index
with Pre => Position = No_Element or else
Has_Element (Container, Position) or else
raise Program_Error,
Post => (if Position = No_Element then To_Index'Result = No_Index
else To_Index'Result in First_Index (Container) ..
Last_Index (Container)),
Nonblocking, Global => null, Use_Formal => null;
27/5function Element (Container : Vector;
Index : Index_Type)
return Element_Type
with Pre => Index in
First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error,
Nonblocking, Global => null, Use_Formal => Element_Type;
function Element (Position : Cursor) return Element_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Element_Type;
28.1/5function Element (Container : Vector;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
29/5procedure Replace_Element (Container : in out Vector;
Index : in Index_Type;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Index in
First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error);
30/5procedure Replace_Element (Container : in out Vector;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
31/5procedure Query_Element
(Container : in Vector;
Index : in Index_Type;
Process : not null access procedure (Element : in Element_Type))
with Pre => Index in
First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error;
32/5procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
32.1/5procedure Query_Element
(Container : in Vector;
Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
33/5procedure Update_Element
(Container : in out Vector;
Index : in Index_Type;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => Index in
First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error;
34/5procedure Update_Element
(Container : in out Vector;
Position : in Cursor;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
34.1/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
34.3/5function Constant_Reference (Container : aliased in Vector;
Index : in Index_Type)
return Constant_Reference_Type
with Pre => Index in
First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
34.4/5function Reference (Container : aliased in out Vector;
Index : in Index_Type)
return Reference_Type
with Pre => Index in
First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
34.5/5function Constant_Reference (Container : aliased in Vector;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
34.6/5function Reference (Container : aliased in out Vector;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
34.7/5procedure Assign (Target : in out Vector; Source : in Vector)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target) and then
Capacity (Target) >= Length (Target);
34.8/5function Copy (Source : Vector; Capacity : Count_Type := 0)
return Vector
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post => Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result)
and then
not Tampering_With_Cursors_Prohibited (Copy'Result)
and then
Copy'Result.Capacity >= (if Capacity = 0 then
Length (Source) else Capacity);
35/5procedure Move (Target : in out Vector;
Source : in out Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Length (Target) = Length (Source)'Old and then
Length (Source) = 0 and then
Capacity (Target) >= Length (Source)'Old);
36/5procedure Insert_Vector (Container : in out Vector;
Before : in Extended_Index;
New_Item : in Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before in
First_Index (Container) .. Last_Index (Container) + 1
or else raise Constraint_Error) and then
(Length (Container) <= Maximum_Length - Length (New_Item)
or else raise Constraint_Error),
Post => Length (Container)'Old + Length (New_Item) =
Length (Container) and then
Capacity (Container) >= Length (Container);
37/5procedure Insert_Vector (Container : in out Vector;
Before : in Cursor;
New_Item : in Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Length (New_Item)
or else raise Constraint_Error),
Post => Length (Container)'Old + Length (New_Item) =
Length (Container) and then
Capacity (Container) >= Length (Container);
38/5procedure Insert_Vector (Container : in out Vector;
Before : in Cursor;
New_Item : in Vector;
Position : out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Length (New_Item)
or else raise Constraint_Error),
Post => Length (Container)'Old + Length (New_Item) =
Length (Container) and then
Has_Element (Container, Position) and then
Capacity (Container) >= Length (Container);
39/5procedure Insert (Container : in out Vector;
Before : in Extended_Index;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before in
First_Index (Container) .. Last_Index (Container) + 1
or else raise Constraint_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count =
Length (Container) and then
Capacity (Container) >= Length (Container);
40/5procedure Insert (Container : in out Vector;
Before : in Cursor;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count =
Length (Container) and then
Capacity (Container) >= Length (Container);
41/5procedure Insert (Container : in out Vector;
Before : in Cursor;
New_Item : in Element_Type;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count =
Length (Container) and then
Has_Element (Container, Position) and then
Capacity (Container) >= Length (Container);
42/5procedure Insert (Container : in out Vector;
Before : in Extended_Index;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before in
First_Index (Container) .. Last_Index (Container) + 1
or else raise Constraint_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count =
Length (Container) and then
Capacity (Container) >= Length (Container);
43/5procedure Insert (Container : in out Vector;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container)
and then Has_Element (Container, Position) and then
Capacity (Container) >= Length (Container);
44/5procedure Prepend_Vector (Container : in out Vector;
New_Item : in Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Length (New_Item)
or else raise Constraint_Error),
Post => Length (Container)'Old + Length (New_Item) =
Length (Container) and then
Capacity (Container) >= Length (Container);
45/5procedure Prepend (Container : in out Vector;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count =
Length (Container) and then
Capacity (Container) >= Length (Container);
46/5procedure Append_Vector (Container : in out Vector;
New_Item : in Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Length (New_Item)
or else raise Constraint_Error),
Post => Length (Container)'Old + Length (New_Item) =
Length (Container) and then
Capacity (Container) >= Length (Container);
47/5procedure Append (Container : in out Vector;
New_Item : in Element_Type;
Count : in Count_Type )
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post =>
Length (Container)'Old + Count = Length (Container) and then
Capacity (Container) >= Length (Container);
47.1/5procedure Append (Container : in out Vector;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - 1
or else raise Constraint_Error),
Post => Length (Container)'Old + 1 = Length (Container) and then
Capacity (Container) >= Length (Container);
48/5procedure Insert_Space (Container : in out Vector;
Before : in Extended_Index;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before in
First_Index (Container) .. Last_Index (Container) + 1
or else raise Constraint_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count =
Length (Container) and then
Capacity (Container) >= Length (Container);
49/5procedure Insert_Space (Container : in out Vector;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count =
Length (Container) and then
Has_Element (Container, Position) and then
Capacity (Container) >= Length (Container);
50/5procedure Delete (Container : in out Vector;
Index : in Extended_Index;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Index in
First_Index (Container) .. Last_Index (Container) + 1
or else raise Constraint_Error),
Post => Length (Container)'Old - Count <=
Length (Container);
51/5procedure Delete (Container : in out Vector;
Position : in out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Length (Container)'Old - Count <=
Length (Container) and then
Position = No_Element;
52/5procedure Delete_First (Container : in out Vector;
Count : in Count_Type := 1)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container)'Old - Count <= Length (Container);
53/5procedure Delete_Last (Container : in out Vector;
Count : in Count_Type := 1)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container)'Old - Count <= Length (Container);
54/5procedure Reverse_Elements (Container : in out Vector)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error;
55/5procedure Swap (Container : in out Vector;
I, J : in Index_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(I in First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error) and then
(J in First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error);
56/5procedure Swap (Container : in out Vector;
I, J : in Cursor)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(I /= No_Element or else Constraint_Error) and then
(J /= No_Element or else Constraint_Error) and then
(Has_Element (Container, I)
or else raise Program_Error) and then
(Has_Element (Container, J)
or else raise Program_Error);
57/5function First_Index (Container : Vector) return Index_Type
with Nonblocking, Global => null, Use_Formal => null,
Post => First_Index'Result = Index_Type'First;
58/5function First (Container : Vector) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, First'Result)
else First'Result = No_Element);
59/5function First_Element (Container : Vector)
return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
60/5function Last_Index (Container : Vector) return Extended_Index
with Nonblocking, Global => null, Use_Formal => null,
Post => (if Length (Container) = 0
then Last_Index'Result = No_Index
else Count_Type(Last_Index'Result - Index_Type'First) =
Length (Container) - 1);
61/5function Last (Container : Vector) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, Last'Result)
else Last'Result = No_Element);
62/5function Last_Element (Container : Vector)
return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
63/5function Next (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then Next'Result = No_Element);
63.1/5function Next (Container : Vector; Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Next'Result = No_Element
elsif Has_Element (Container, Next'Result) then
To_Index (Container, Next'Result) =
To_Index (Container, Position) + 1
elsif Next'Result = No_Element then
Position = Last (Container)
else False);
64/5procedure Next (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
64.1/5procedure Next (Container : in Vector;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
65/5function Previous (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element
then Previous'Result = No_Element);
65.1/5function Previous (Container : Vector;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element
then Previous'Result = No_Element
elsif Has_Element (Container, Previous'Result) then
To_Index (Container, Previous'Result) =
To_Index (Container, Position) - 1
elsif Previous'Result = No_Element then
Position = First (Container)
else False);
66/5procedure Previous (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
66.1/5procedure Previous (Container : in Vector;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
67/2function Find_Index (Container : Vector;
Item : Element_Type;
Index : Index_Type := Index_Type'First)
return Extended_Index;
68/5function Find (Container : Vector;
Item : Element_Type;
Position : Cursor := No_Element)
return Cursor
with Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
69/2function Reverse_Find_Index (Container : Vector;
Item : Element_Type;
Index : Index_Type := Index_Type'Last)
return Extended_Index;
70/5function Reverse_Find (Container : Vector;
Item : Element_Type;
Position : Cursor := No_Element)
return Cursor
with Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Reverse_Find'Result /= No_Element
then Has_Element (Container, Reverse_Find'Result));
71/2function Contains (Container : Vector;
Item : Element_Type) return Boolean;
72/3This paragraph was deleted.
73/5procedure Iterate
(Container : in Vector;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
74/5procedure Reverse_Iterate
(Container : in Vector;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
74.1/5function Iterate (Container : in Vector)
return Vector_Iterator_Interfaces.Parallel_Reversible_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
74.2/5function Iterate (Container : in Vector; Start : in Cursor)
return Vector_Iterator_Interfaces.Reversible_Iterator'Class
with Pre => (Start /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Start)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
75/5generic
with function "<" (Left, Right : Element_Type)
return Boolean is <>;
package Generic_Sorting
with Nonblocking, Global => null is
76/2function Is_Sorted (Container : Vector) return Boolean;
77/5procedure Sort (Container : in out Vector)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error;
78/5procedure Merge (Target : in out Vector;
Source : in out Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Length (Target) <= Maximum_Length - Length (Source)
or else raise Constraint_Error) and then
((Length (Source) = 0 or else
not Target'Has_Same_Storage (Source))
or else raise Program_Error),
Post => (declare
Result_Length : constant Count_Type :=
Length (Source)'Old + Length (Target)'Old;
begin
(Length (Source) = 0 and then
Length (Target) = Result_Length and then
Capacity (Target) >= Result_Length));
79/2end Generic_Sorting;
79.1/5package Stable is
79.2/5type Vector (Base : not null access Vectors.Vector) is
tagged limited private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Stable_Properties => (Length, Capacity),
Global => null,
Default_Initial_Condition => Length (Vector) = 0,
Preelaborable_Initialization;
type Cursor is private
with Preelaborable_Initialization;
79.4/5Empty_Vector : constant Vector;
79.5/5No_Element : constant Cursor;
79.6/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
79.7/5package Vector_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
79.8/5procedure Assign (Target : in out Vectors.Vector;
Source : in Vector)
with Post => Length (Source) = Length (Target) and then
Capacity (Target) >= Length (Target);
79.9/5function Copy (Source : Vectors.Vector) return Vector
with Post => Length (Copy'Result) = Length (Source);
79.10/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null, Use_Formal => null,
Default_Initial_Condition => (raise Program_Error);
79.11/5type Reference_Type
(Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null, Use_Formal => null,
Default_Initial_Condition => (raise Program_Error);
79.12/5-- Additional subprograms as described in the text
-- are declared here.
79.13/5private
79.14/5... -- not specified by the language
79.15/5end Stable;
80/2private
81/2... -- not specified by the language
82/2end Ada.Containers.Vectors;
The actual function for the generic formal function "=" on Element_Type values is expected to define a reflexive and symmetric relationship and return the same result value each time it is called with a particular pair of values. If it behaves in some other manner, the functions defined to use it return an unspecified value. The exact arguments and number of calls of this generic formal function by the functions defined to use it are unspecified.
The type Vector is used to represent vectors. The type Vector needs finalization (see 7.6).
Empty_Vector represents the empty vector object. It has a length of 0. If an object of type Vector is not otherwise initialized, it is initialized to the same value as Empty_Vector.
No_Element represents a cursor that designates no element. If an object of type Cursor is not otherwise initialized, it is initialized to the same value as No_Element.
The primitive "=" operator for type Cursor returns True if both cursors are No_Element, or designate the same element in the same container.
Execution of the default implementation of the Input, Output, Read, or Write attribute of type Cursor raises Program_Error.
Vector'Write for a Vector object V writes Length(V) elements of the vector to the stream. It may also write additional information about the vector.
Vector'Read reads the representation of a vector from the stream, and assigns to Item a vector with the same length and elements as was written by Vector'Write.
No_Index represents a position that does not correspond to any element. The subtype Extended_Index includes the indices covered by Index_Type plus the value No_Index and, if it exists, the successor to the Index_Type'Last.
[Some operations check for “tampering with cursors” of a container because they depend on the set of elements of the container remaining constant, and others check for “tampering with elements” of a container because they depend on elements of the container not being replaced.] When tampering with cursors is prohibited for a particular vector object V, Program_Error is propagated by the finalization of V[, as well as by a call that passes V to certain of the operations of this package, as indicated by the precondition of such an operation]. Similarly, when tampering with elements is prohibited for V, Program_Error is propagated by a call that passes V to certain of the other operations of this package, as indicated by the precondition of such an operation.
Paragraphs 91 through 97 are removed as preconditions now describe these rules.
assignment_statement, because that finalizes the target object as part of the operation, and finalization of an object is already defined as tampering with cursors.
function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
Returns True if Position designates an element, and returns False otherwise.
function Has_Element (Container : Vector; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if Position designates an element in Container, and returns False otherwise.
function "=" (Left, Right : Vector) return Boolean;
If Left and Right denote the same vector object, then the function returns True. If Left and Right have different lengths, then the function returns False. Otherwise, it compares each element in Left to the corresponding element in Right using the generic formal equality operator. If any such comparison returns False, the function returns False; otherwise, it returns True. Any exception raised during evaluation of element equality is propagated.
function Tampering_With_Cursors_Prohibited
(Container : Vector) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if tampering with cursors or tampering with elements is currently prohibited for Container, and returns False otherwise.
function Tampering_With_Elements_Prohibited
(Container : Vector) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Always returns False[, regardless of whether tampering with elements is prohibited].
function Maximum_Length return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
Returns the maximum Length of a Vector, based on the index type.
Count_Type (Index_Type'Last - Index_Type'First + 1)
function Empty (Capacity : Count_Type := implementation-defined)
return Vector
with Pre => Capacity <= Maximum_Length
or else raise Constraint_Error,
Post =>
Capacity (Empty'Result) >= Capacity and then
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
Returns an empty vector.
function To_Vector (Length : Count_Type) return Vector
with Pre => Length <= Maximum_Length or else raise Constraint_Error,
Post =>
To_Vector'Result.Length = Length and then
not Tampering_With_Elements_Prohibited (To_Vector'Result)
and then
not Tampering_With_Cursors_Prohibited (To_Vector'Result)
and then
To_Vector'Result.Capacity >= Length;
Returns a vector with a length of Length, filled with empty elements.
function To_Vector
(New_Item : Element_Type;
Length : Count_Type) return Vector
with Pre => Length <= Maximum_Length or else raise Constraint_Error,
Post =>
To_Vector'Result.Length = Length and then
not Tampering_With_Elements_Prohibited (To_Vector'Result)
and then
not Tampering_With_Cursors_Prohibited (To_Vector'Result)
and then
To_Vector'Result.Capacity >= Length;
Returns a vector with a length of Length, filled with elements initialized to the value New_Item.
function "&" (Left, Right : Vector) return Vector
with Pre => Length (Left) <= Maximum_Length - Length (Right)
or else raise Constraint_Error,
Post => Length (Vectors."&"'Result) =
Length (Left) + Length (Right) and then
not Tampering_With_Elements_Prohibited (Vectors."&"'Result)
and then
not Tampering_With_Cursors_Prohibited (Vectors."&"'Result)
and then
Vectors."&"'Result.Capacity >=
Length (Left) + Length (Right);
Returns a vector comprising the elements of Left followed by the elements of Right.
function "&" (Left : Vector;
Right : Element_Type) return Vector
with Pre => Length (Left) <= Maximum_Length - 1
or else raise Constraint_Error,
Post => Vectors."&"'Result.Length = Length (Left) + 1 and then
not Tampering_With_Elements_Prohibited (Vectors."&"'Result)
and then
not Tampering_With_Cursors_Prohibited (Vectors."&"'Result)
and then
Vectors."&"'Result.Capacity >= Length (Left) + 1;
Returns a vector comprising the elements of Left followed by the element Right.
function "&" (Left : Element_Type;
Right : Vector) return Vector
with Pre => Length (Right) <= Maximum_Length - 1
or else raise Constraint_Error,
Post => Length (Vectors."&"'Result) = Length (Right) + 1 and then
not Tampering_With_Elements_Prohibited (Vectors."&"'Result)
and then
not Tampering_With_Cursors_Prohibited (Vectors."&"'Result)
and then
Vectors."&"'Result.Capacity >= Length (Right) + 1;
Returns a vector comprising the element Left followed by the elements of Right.
function "&" (Left, Right : Element_Type) return Vector
with Pre => Maximum_Length >= 2 or else raise Constraint_Error,
Post => Length ("&"'Result) = 2 and then
not Tampering_With_Elements_Prohibited (Vectors."&"'Result)
and then
not Tampering_With_Cursors_Prohibited (Vectors."&"'Result)
and then
Vectors."&"'Result.Capacity >= 2;
Returns a vector comprising the element Left followed by the element Right.
function Capacity (Container : Vector) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
Returns the capacity of Container.
procedure Reserve_Capacity (Container : in out Vector;
Capacity : in Count_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Container.Capacity >= Capacity;
If the capacity of Container is already greater than or equal to Capacity, then Reserve_Capacity has no effect. Otherwise, Reserve_Capacity allocates additional storage as necessary to ensure that the length of the resulting vector can become at least the value Capacity without requiring an additional call to Reserve_Capacity, and is large enough to hold the current length of Container. Reserve_Capacity then, as necessary, moves elements into the new storage and deallocates any storage no longer needed. Any exception raised during allocation is propagated and Container is not modified.
function Length (Container : Vector) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
Returns the number of elements in Container.
procedure Set_Length (Container : in out Vector;
Length : in Count_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length <= Maximum_Length or else raise Constraint_Error),
Post => Container.Length = Length and then
Capacity (Container) >= Length;
If Length is larger than the capacity of Container, Set_Length calls Reserve_Capacity (Container, Length), then sets the length of the Container to Length. If Length is greater than the original length of Container, empty elements are added to Container; otherwise, elements are removed from Container.
function Is_Empty (Container : Vector) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Length (Container) = 0);
Returns True if Container is empty .
procedure Clear (Container : in out Vector)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = 0;
Removes all the elements from Container. The capacity of Container does not change.
function To_Cursor (Container : Vector;
Index : Extended_Index) return Cursor
with Post => (if Index in
First_Index (Container) .. Last_Index (Container)
then Has_Element (Container, To_Cursor'Result)
else To_Cursor'Result = No_Element),
Nonblocking, Global => null, Use_Formal => null;
Returns a cursor designating the element at position Index in Container; returns No_Element if Index does not designate an element . For the purposes of determining whether the parameters overlap in a call to To_Cursor, the Container parameter is not considered to overlap with any object [(including itself)].
function To_Index (Position : Cursor) return Extended_Index
with Nonblocking, Global => in all, Use_Formal => null;
If Position is No_Element, No_Index is returned. Otherwise, the index (within its containing vector) of the element designated by Position is returned.
function To_Index (Container : Vector;
Position : Cursor) return Extended_Index
with Pre => Position = No_Element or else
Has_Element (Container, Position) or else
raise Program_Error,
Post => (if Position = No_Element then To_Index'Result = No_Index
else To_Index'Result in First_Index (Container) ..
Last_Index (Container)),
Nonblocking, Global => null, Use_Formal => null;
Returns the index (within Container) of the element designated by Position; returns No_Index if Position does not designate an element. For the purposes of determining whether the parameters overlap in a call to To_Index, the Container parameter is not considered to overlap with any object [(including itself)].
function Element (Container : Vector;
Index : Index_Type)
return Element_Type
with Pre => Index in First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error,
Nonblocking, Global => null, Use_Formal => Element_Type;
Element returns the element at position Index.
function Element (Position : Cursor) return Element_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Element_Type;
Element returns the element designated by Position.
function Element (Container : Vector;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
Element returns the element designated by Position in Container.
procedure Replace_Element (Container : in out Vector;
Index : in Index_Type;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Index in First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error);
Replace_Element assigns the value New_Item to the element at position Index. Any exception raised during the assignment is propagated. The element at position Index is not an empty element after successful call to Replace_Element. For the purposes of determining whether the parameters overlap in a call to Replace_Element, the Container parameter is not considered to overlap with any object [(including itself)], and the Index parameter is considered to overlap with the element at position Index.
procedure Replace_Element (Container : in out Vector;
Position : in Cursor;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Replace_Element assigns New_Item to the element designated by Position. Any exception raised during the assignment is propagated. The element at Position is not an empty element after successful call to Replace_Element. For the purposes of determining whether the parameters overlap in a call to Replace_Element, the Container parameter is not considered to overlap with any object [(including itself)].
procedure Query_Element
(Container : in Vector;
Index : in Index_Type;
Process : not null access procedure (Element : in Element_Type))
with Pre => Index in First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error;
Query_Element calls Process.all with the element at position Index as the argument. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => Position /= No_Element or else raise Constraint_Error
Global => in all;
Query_Element calls Process.all with the element designated by Position as the argument. Tampering with the elements of the vector that contains the element designated by Position is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Query_Element
(Container : in Vector;
Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Query_Element calls Process.all with the element designated by Position as the argument. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Update_Element
(Container : in out Vector;
Index : in Index_Type;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => Index in First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error;
Update_Element calls Process.all with the element at position Index as the argument. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all shall be unconstrained.
The element at position Index is not an empty element after successful completion of this operation.
procedure Update_Element
(Container : in out Vector;
Position : in Cursor;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Update_Element calls Process.all with the element designated by Position as the argument. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all shall be unconstrained.
The element designated by Position is not an empty element after successful completion of this operation.
type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
147.2/5type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
The types Constant_Reference_Type and Reference_Type need finalization.
This paragraph was deleted.
function Constant_Reference (Container : aliased in Vector;
Index : in Index_Type)
return Constant_Reference_Type
with Pre => Index in First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read access to an individual element of a vector given an index value.
Constant_Reference returns an object whose discriminant is an access value that designates the element at position Index. Tampering with the elements of Container is prohibited while the object returned by Constant_Reference exists and has not been finalized.
function Reference (Container : aliased in out Vector;
Index : in Index_Type)
return Reference_Type
with Pre => Index in First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read and write access to an individual element of a vector given an index value.
Reference returns an object whose discriminant is an access value that designates the element at position Index. Tampering with the elements of Container is prohibited while the object returned by Reference exists and has not been finalized.
The element at position Index is not an empty element after successful completion of this operation.
function Constant_Reference (Container : aliased in Vector;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read access to an individual element of a vector given a cursor.
Constant_Reference returns an object whose discriminant is an access value that designates the element designated by Position. Tampering with the elements of Container is prohibited while the object returned by Constant_Reference exists and has not been finalized.
function Reference (Container : aliased in out Vector;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read and write access to an individual element of a vector given a cursor.
Reference returns an object whose discriminant is an access value that designates the element designated by Position. Tampering with the elements of Container is prohibited while the object returned by Reference exists and has not been finalized.
The element designated by Position is not an empty element after successful completion of this operation.
procedure Assign (Target : in out Vector; Source : in Vector)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target) and then
Capacity (Target) >= Length (Target);
If Target denotes the same object as Source, the operation has no effect. If the length of Source is greater than the capacity of Target, Reserve_Capacity (Target, Length (Source)) is called. The elements of Source are then copied to Target as for an assignment_statement assigning Source to Target (this includes setting the length of Target to be that of Source).
function Copy (Source : Vector; Capacity : Count_Type := 0)
return Vector
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post => Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result)
and then
not Tampering_With_Cursors_Prohibited (Copy'Result)
and then
Copy'Result.Capacity >= (if Capacity = 0 then
Length (Source) else Capacity);
Returns a vector whose elements are initialized from the corresponding elements of Source.
procedure Move (Target : in out Vector;
Source : in out Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Length (Target) = Length (Source)'Old and then
Length (Source) = 0 and then
Capacity (Target) >= Length (Source)'Old);
If Target denotes the same object as Source, then the operation has no effect. Otherwise, Move first calls Reserve_Capacity (Target, Length (Source)) and then Clear (Target); then, each element from Source is removed from Source and inserted into Target in the original order.
procedure Insert_Vector (Container : in out Vector;
Before : in Extended_Index;
New_Item : in Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before in
First_Index (Container) .. Last_Index (Container) + 1
or else raise Constraint_Error) and then
(Length (Container) <= Maximum_Length - Length (New_Item)
or else raise Constraint_Error),
Post => Length (Container)'Old + Length (New_Item) =
Length (Container) and then
Capacity (Container) >= Length (Container);
If Length(New_Item) is 0, then Insert_Vector does nothing. Otherwise, it computes the new length NL as the sum of the current length and Length (New_Item); if the value of Last appropriate for length NL would be greater than Index_Type'Last, then Constraint_Error is propagated.
If the current vector capacity is less than NL, Reserve_Capacity (Container, NL) is called to increase the vector capacity. Then Insert_Vector slides the elements in the range Before .. Last_Index (Container) up by Length(New_Item) positions, and then copies the elements of New_Item to the positions starting at Before. Any exception raised during the copying is propagated.
procedure Insert_Vector (Container : in out Vector;
Before : in Cursor;
New_Item : in Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Length (New_Item)
or else raise Constraint_Error),
Post => Length (Container)'Old + Length (New_Item) =
Length (Container) and then
Capacity (Container) >= Length (Container);
If Length(New_Item) is 0, then Insert_Vector does nothing. If Before is No_Element, then the call is equivalent to Insert_Vector (Container, Last_Index (Container) + 1, New_Item); otherwise, the call is equivalent to Insert_Vector (Container, To_Index (Before), New_Item);
procedure Insert_Vector (Container : in out Vector;
Before : in Cursor;
New_Item : in Vector;
Position : out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Length (New_Item)
or else raise Constraint_Error),
Post => Length (Container)'Old + Length (New_Item) =
Length (Container) and then
Has_Element (Container, Position) and then
Capacity (Container) >= Length (Container);
If Before equals No_Element, then let T be Last_Index (Container) + 1; otherwise, let T be To_Index (Before). Insert_Vector (Container, T, New_Item) is called, and then Position is set to To_Cursor (Container, T).
procedure Insert (Container : in out Vector;
Before : in Extended_Index;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before in
First_Index (Container) .. Last_Index (Container) + 1
or else raise Constraint_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container) and then
Capacity (Container) >= Length (Container);
Equivalent to Insert (Container, Before, To_Vector (New_Item, Count));
procedure Insert (Container : in out Vector;
Before : in Cursor;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container) and then
Capacity (Container) >= Length (Container);
Equivalent to Insert (Container, Before, To_Vector (New_Item, Count));
procedure Insert (Container : in out Vector;
Before : in Cursor;
New_Item : in Element_Type;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container) and then
Has_Element (Container, Position) and then
Capacity (Container) >= Length (Container);
Equivalent to Insert (Container, Before, To_Vector (New_Item, Count), Position);
procedure Insert (Container : in out Vector;
Before : in Extended_Index;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before in
First_Index (Container) .. Last_Index (Container) + 1
or else raise Constraint_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container) and then
Capacity (Container) >= Length (Container);
If Count is 0, then Insert does nothing. Otherwise, it computes the new length NL as the sum of the current length and Count; if the value of Last appropriate for length NL would be greater than Index_Type'Last, then Constraint_Error is propagated.
If the current vector capacity is less than NL, Reserve_Capacity (Container, NL) is called to increase the vector capacity. Then Insert slides the elements in the range Before .. Last_Index (Container) up by Count positions, and then inserts elements that are initialized by default (see 3.3.1) in the positions starting at Before.
procedure Insert (Container : in out Vector;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container) and then
Has_Element (Container, Position) and then
Capacity (Container) >= Length (Container);
If Before equals No_Element, then let T be Last_Index (Container) + 1; otherwise, let T be To_Index (Before). Insert (Container, T, Count) is called, and then Position is set to To_Cursor (Container, T).
procedure Prepend_Vector (Container : in out Vector;
New_Item : in Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Length (New_Item)
or else raise Constraint_Error),
Post => Length (Container)'Old + Length (New_Item) =
Length (Container) and then
Capacity (Container) >= Length (Container);
Equivalent to Insert (Container, First_Index (Container), New_Item).
procedure Prepend (Container : in out Vector;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container) and then
Capacity (Container) >= Length (Container);
Equivalent to Insert (Container, First_Index (Container), New_Item, Count).
procedure Append_Vector (Container : in out Vector;
New_Item : in Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Length (New_Item)
or else raise Constraint_Error),
Post => Length (Container)'Old + Length (New_Item) =
Length (Container) and then
Capacity (Container) >= Length (Container);
Equivalent to Insert (Container, Last_Index (Container) + 1, New_Item).
procedure Append (Container : in out Vector;
New_Item : in Element_Type;
Count : in Count_Type )
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container) and then
Capacity (Container) >= Length (Container);
Equivalent to Insert (Container, Last_Index (Container) + 1, New_Item, Count).
procedure Append (Container : in out Vector;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - 1
or else raise Constraint_Error),
Post => Length (Container)'Old + 1 = Length (Container) and then
Capacity (Container) >= Length (Container);
Equivalent to Insert (Container, Last_Index (Container) + 1, New_Item, 1).
procedure Insert_Space (Container : in out Vector;
Before : in Extended_Index;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before in
First_Index (Container) .. Last_Index (Container) + 1
or else raise Constraint_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container) and then
Capacity (Container) >= Length (Container);
If Count is 0, then Insert_Space does nothing. Otherwise, it computes the new length NL as the sum of the current length and Count; if the value of Last appropriate for length NL would be greater than Index_Type'Last, then Constraint_Error is propagated.
If the current vector capacity is less than NL, Reserve_Capacity (Container, NL) is called to increase the vector capacity. Then Insert_Space slides the elements in the range Before .. Last_Index (Container) up by Count positions, and then inserts empty elements in the positions starting at Before.
procedure Insert_Space (Container : in out Vector;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Maximum_Length - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container) and then
Has_Element (Container, Position) and then
Capacity (Container) >= Length (Container);
If Before equals No_Element, then let T be Last_Index (Container) + 1; otherwise, let T be To_Index (Before). Insert_Space (Container, T, Count) is called, and then Position is set to To_Cursor (Container, T).
procedure Delete (Container : in out Vector;
Index : in Extended_Index;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Index in
First_Index (Container) .. Last_Index (Container) + 1
or else raise Constraint_Error),
Post => Length (Container)'Old - Count <= Length (Container);
If Count is 0, Delete has no effect. Otherwise, Delete slides the elements (if any) starting at position Index + Count down to Index. Any exception raised during element assignment is propagated.
procedure Delete (Container : in out Vector;
Position : in out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Length (Container)'Old - Count <= Length (Container)
and then Position = No_Element;
Delete (Container, To_Index (Position), Count) is called, and then Position is set to No_Element.
procedure Delete_First (Container : in out Vector;
Count : in Count_Type := 1)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container)'Old - Count <= Length (Container);
Equivalent to Delete (Container, First_Index (Container), Count).
procedure Delete_Last (Container : in out Vector;
Count : in Count_Type := 1)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container)'Old - Count <= Length (Container);
If Length (Container) <= Count, then Delete_Last is equivalent to Clear (Container). Otherwise, it is equivalent to Delete (Container, Index_Type'Val(Index_Type'Pos(Last_Index (Container)) – Count + 1), Count).
procedure Reverse_Elements (Container : in out Vector)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error;
Reorders the elements of Container in reverse order.
procedure Swap (Container : in out Vector;
I, J : in Index_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(I in First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error) and then
(J in First_Index (Container) .. Last_Index (Container)
or else raise Constraint_Error);
Swap exchanges the values of the elements at positions I and J.
procedure Swap (Container : in out Vector;
I, J : in Cursor)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(I /= No_Element or else Constraint_Error) and then
(J /= No_Element or else Constraint_Error) and then
(Has_Element (Container, I)
or else raise Program_Error) and then
(Has_Element (Container, J)
or else raise Program_Error);
Swap exchanges the values of the elements designated by I and J.
function First_Index (Container : Vector) return Index_Type
with Nonblocking, Global => null, Use_Formal => null,
Post => First_Index'Result = Index_Type'First;
Returns the value Index_Type'First.
function First (Container : Vector) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, First'Result)
else First'Result = No_Element);
If Container is empty, First returns No_Element. Otherwise, it returns a cursor that designates the first element in Container.
function First_Element (Container : Vector)
return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
Equivalent to Element (Container, First_Index (Container)).
function Last_Index (Container : Vector) return Extended_Index
with Nonblocking, Global => null, Use_Formal => null,
Post => (if Length (Container) = 0 then Last_Index'Result = No_Index
else Count_Type(Last_Index'Result - Index_Type'First) =
Length (Container) - 1);
If Container is empty, Last_Index returns No_Index. Otherwise, it returns the position of the last element in Container.
function Last (Container : Vector) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, Last'Result)
else Last'Result = No_Element);
If Container is empty, Last returns No_Element. Otherwise, it returns a cursor that designates the last element in Container.
function Last_Element (Container : Vector)
return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
Equivalent to Element (Container, Last_Index (Container)).
function Next (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then Next'Result = No_Element);
If Position equals No_Element or designates the last element of the container, then Next returns the value No_Element. Otherwise, it returns a cursor that designates the element with index To_Index (Position) + 1 in the same vector as Position.
function Next (Container : Vector;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Next'Result = No_Element
elsif Has_Element (Container, Next'Result) then
To_Index (Container, Next'Result) =
To_Index (Container, Position) + 1
elsif Next'Result = No_Element then
Position = Last (Container)
else False);
Returns a cursor designating the next element in Container, if any.
procedure Next (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
Equivalent to Position := Next (Position).
procedure Next (Container : in Vector;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
Equivalent to Position := Next (Container, Position).
function Previous (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element
then Previous'Result = No_Element);
If Position equals No_Element or designates the first element of the container, then Previous returns the value No_Element. Otherwise, it returns a cursor that designates the element with index To_Index (Position) – 1 in the same vector as Position.
function Previous (Container : Vector;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Previous'Result = No_Element
elsif Has_Element (Container, Previous'Result) then
To_Index (Container, Previous'Result) =
To_Index (Container, Position) - 1
elsif Previous'Result = No_Element then
Position = First (Container)
else False);
Returns a cursor designating the previous element in Container, if any.
procedure Previous (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
Equivalent to Position := Previous (Position).
procedure Previous (Container : in Vector;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
Equivalent to Position := Previous (Container, Position).
function Find_Index (Container : Vector;
Item : Element_Type;
Index : Index_Type := Index_Type'First)
return Extended_Index;
Searches the elements of Container for an element equal to Item (using the generic formal equality operator). The search starts at position Index and proceeds towards Last_Index (Container). If no equal element is found, then Find_Index returns No_Index. Otherwise, it returns the index of the first equal element encountered.
function Find (Container : Vector;
Item : Element_Type;
Position : Cursor := No_Element)
return Cursor
with Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
Find searches the elements of Container for an element equal to Item (using the generic formal equality operator). The search starts at the first element if Position equals No_Element, and at the element designated by Position otherwise. It proceeds towards the last element of Container. If no equal element is found, then Find returns No_Element. Otherwise, it returns a cursor designating the first equal element encountered.
function Reverse_Find_Index (Container : Vector;
Item : Element_Type;
Index : Index_Type := Index_Type'Last)
return Extended_Index;
Searches the elements of Container for an element equal to Item (using the generic formal equality operator). The search starts at position Index or, if Index is greater than Last_Index (Container), at position Last_Index (Container). It proceeds towards First_Index (Container). If no equal element is found, then Reverse_Find_Index returns No_Index. Otherwise, it returns the index of the first equal element encountered.
function Reverse_Find (Container : Vector;
Item : Element_Type;
Position : Cursor := No_Element)
return Cursor
with Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Reverse_Find'Result /= No_Element
then Has_Element (Container, Reverse_Find'Result));
Reverse_Find searches the elements of Container for an element equal to Item (using the generic formal equality operator). The search starts at the last element if Position equals No_Element, and at the element designated by Position otherwise. It proceeds towards the first element of Container. If no equal element is found, then Reverse_Find returns No_Element. Otherwise, it returns a cursor designating the first equal element encountered.
function Contains (Container : Vector;
Item : Element_Type) return Boolean;
Equivalent to Has_Element (Find (Container, Item)).
Paragraphs 225 and 226 were moved above.
procedure Iterate
(Container : in Vector;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
Invokes Process.all with a cursor that designates each element in Container, in index order. Tampering with the cursors of Container is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
procedure Reverse_Iterate
(Container : in Vector;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
Iterates over the elements in Container as per procedure Iterate, except that elements are traversed in reverse index order.
function Iterate (Container : in Vector)
return Vector_Iterator_Interfaces.Parallel_Reversible_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each node in Container, starting with the first node and moving the cursor as per the Next function when used as a forward iterator, and starting with the last node and moving the cursor as per the Previous function when used as a reverse iterator, and processing all nodes concurrently when used as a parallel iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
function Iterate (Container : in Vector; Start : in Cursor)
return Vector_Iterator_Interfaces.Reversible_Iterator'Class
with Pre => (Start /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Start)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns a reversible iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each node in Container, starting with the node designated by Start and moving the cursor as per the Next function when used as a forward iterator, or moving the cursor as per the Previous function when used as a reverse iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
exit when Cur = Stop;
The actual function for the generic formal function "<" of Generic_Sorting is expected to return the same value each time it is called with a particular pair of element values. It should define a strict weak ordering relationship (see A.18); it should not modify Container. If the actual for "<" behaves in some other manner, the behavior of the subprograms of Generic_Sorting are unspecified. The number of times the subprograms of Generic_Sorting call "<" is unspecified.
function Is_Sorted (Container : Vector) return Boolean;
Returns True if the elements are sorted smallest first as determined by the generic formal "<" operator; otherwise, Is_Sorted returns False. Any exception raised during evaluation of "<" is propagated.
procedure Sort (Container : in out Vector)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error;
Reorders the elements of Container such that the elements are sorted smallest first as determined by the generic formal "<" operator provided. Any exception raised during evaluation of "<" is propagated.
procedure Merge (Target : in out Vector;
Source : in out Vector)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Length (Target) <= Maximum_Length - Length (Source)
or else raise Constraint_Error) and then
((Length (Source) = 0 or else
not Target'Has_Same_Storage (Source))
or else raise Program_Error),
Post => (declare
Result_Length : constant Count_Type :=
Length (Source)'Old + Length (Target)'Old;
begin
(Length (Source) = 0 and then
Length (Target) = Result_Length and then
Capacity (Target) >= Result_Length));
Merge removes elements from Source and inserts them into Target; afterwards, Target contains the union of the elements that were initially in Source and Target; Source is left empty. If Target and Source are initially sorted smallest first, then Target is ordered smallest first as determined by the generic formal "<" operator; otherwise, the order of elements in Target is unspecified. Any exception raised during evaluation of "<" is propagated.
The nested package Vectors.Stable provides a type Stable.Vector that represents a stable vector, which is one that cannot grow and shrink. Such a vector can be created by calling the To_Vector or Copy functions, or by establishing a stabilized view of an ordinary vector.
The subprograms of package Containers.Vectors that have a parameter or result of type Vector are included in the nested package Stable with the same specification, except that the following are omitted:
Tampering_With_Cursors_Prohibited, Tampering_With_Elements_Prohibited, Reserve_Capacity, Assign, Move, Insert, Insert_Space, Insert_Vector, Append, Append_Vector, Prepend, Prepend_Vector, Clear, Delete, Delete_First, Delete_Last, and Set_Length
The generic package Generic_Sorting is also included with the same specification, except that Merge is omitted.
The operations of this package are equivalent to those for ordinary vectors, except that the calls to Tampering_With_Cursors_Prohibited and Tampering_With_Elements_Prohibited that occur in preconditions are replaced by False, and any that occur in postconditions are replaced by True.
If a stable vector is declared with the Base discriminant designating a pre-existing ordinary vector, the stable vector represents a stabilized view of the underlying ordinary vector, and any operation on the stable vector is reflected on the underlying ordinary vector. While a stabilized view exists, any operation that tampers with elements performed on the underlying vector is prohibited. The finalization of a stable vector that provides such a view removes this restriction on the underlying ordinary vector [(though some other restriction can exist due to other concurrent iterations or stabilized views)].
If a stable vector is declared without specifying Base, the object is necessarily initialized. The initializing expression of the stable vector, [typically a call on To_Vector or Copy], determines the Length of the vector. The Length of a stable vector never changes after initialization.
Bounded (Run-Time) Errors
238/3Reading the value of an empty element by calling Element, Query_Element, Update_Element, Constant_Reference, Reference, Swap, Is_Sorted, Sort, Merge, "=", Find, or Reverse_Find is a bounded error. The implementation may treat the element as having any normal value (see 13.9.1) of the element type, or raise Constraint_Error or Program_Error before modifying the vector.
Calling Merge in an instance of Generic_Sorting with either Source or Target not ordered smallest first using the provided generic formal "<" operator is a bounded error. Either Program_Error is raised after Target is updated as described for Merge, or the operation works as defined.
It is a bounded error for the actual function associated with a generic formal subprogram, when called as part of an operation of this package, to tamper with elements of any Vector parameter of the operation. Either Program_Error is raised, or the operation works as defined on the value of the Vector either prior to, or subsequent to, some or all of the modifications to the Vector.
It is a bounded error to call any subprogram declared in the visible part of Containers.Vectors when the associated container has been finalized. If the operation takes Container as an in out parameter, then it raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for an empty container, or it raises Constraint_Error or Program_Error.
A Cursor value is ambiguous if any of the following have occurred since it was created:
- Insert, Insert_Space, Insert_Vector, or Delete has been called on the vector that contains the element the cursor designates with an index value (or a cursor designating an element at such an index value) less than or equal to the index value of the element designated by the cursor; or
- The vector that contains the element it designates has been passed to the Sort or Merge procedures of an instance of Generic_Sorting, or to the Reverse_Elements procedure.
It is a bounded error to call any subprogram other than "=" or Has_Element declared in Containers.Vectors with an ambiguous (but not invalid, see below) cursor parameter. Possible results are:
- The cursor may be treated as if it were No_Element;
- The cursor may designate some element in the vector (but not necessarily the element that it originally designated);
- Constraint_Error may be raised; or
- Program_Error may be raised.
Erroneous Execution
248/2A Cursor value is invalid if any of the following have occurred since it was created:
- The vector that contains the element it designates has been finalized;
- The vector that contains the element it designates has been used as the Target of a call to Assign, or as the target of an
assignment_statement; 250/2 - [The vector that contains the element it designates has been used as the Source or Target of a call to Move;] or
- The element it designates has been deleted or removed from the vector that previously contained the element.
The result of "=" or Has_Element is unspecified if it is called with an invalid cursor parameter. Execution is erroneous if any other subprogram declared in Containers.Vectors is called with an invalid cursor parameter.
Execution is erroneous if the vector associated with the result of a call to Reference or Constant_Reference is finalized before the result object returned by the call to Reference or Constant_Reference is finalized.
Implementation Requirements
253/2No storage associated with a vector object shall be lost upon assignment or scope exit.
The execution of an assignment_statement for a vector shall have the effect of copying the elements from the source vector object to the target vector object and changing the length of the target object to that of the source object.
Implementation Advice
255/2Containers.Vectors should be implemented similarly to an array. In particular, if the length of a vector is N, then
- the worst-case time complexity of Element should be O(log N);
- the worst-case time complexity of Append with Count=1 when N is less than the capacity of the vector should be O(log N); and
- the worst-case time complexity of Prepend with Count=1 and Delete_First with Count=1 should be O(N log N).
The worst-case time complexity of a call on procedure Sort of an instance of Containers.Vectors.Generic_Sorting should be O(N**2), and the average time complexity should be better than O(N**2).
Containers.Vectors.Generic_Sorting.Sort and Containers.Vectors.Generic_Sorting.Merge should minimize copying of elements.
Move should not copy elements, and should minimize copying of internal data structures.
If an exception is propagated from a vector operation, no storage should be lost, nor any elements removed from a vector unless specified by the operation.
Extensions to Ada 95
Incompatibilities With Ada 2005
use_clause, and an entity E with the same defining_identifier as a new entity in Containers.Vectors is defined in a package that is also referenced in a use_clause, the entity E may no longer be use-visible, resulting in errors. This should be rare and is easily fixed if it does occur. Extensions to Ada 2005
Wording Changes from Ada 2005
Inconsistencies With Ada 2012
Incompatibilities With Ada 2012
Extensions to Ada 2012
aggregate syntax can be used to create Vectors.Wording Changes from Ada 2012
A.18.3 The Generic Package Containers.Doubly_Linked_Lists
1/2The language-defined generic package Containers.Doubly_Linked_Lists provides private types List and Cursor, and a set of operations for each type. A list container is optimized for insertion and deletion at any position.
A doubly-linked list container object manages a linked list of internal nodes, each of which contains an element and pointers to the next (successor) and previous (predecessor) internal nodes. A cursor designates a particular node within a list (and by extension the element contained in that node). A cursor keeps designating the same node (and element) as long as the node is part of the container, even if the node is moved in the container.
The length of a list is the number of elements it contains.
Static Semantics
4/2The generic library package Containers.Doubly_Linked_Lists has the following declaration:
with Ada.Iterator_Interfaces;
generic
type Element_Type is private;
with function "=" (Left, Right : Element_Type)
return Boolean is <>;
package Ada.Containers.Doubly_Linked_Lists
with Preelaborate, Remote_Types,
Nonblocking, Global => in out synchronized is
type List is tagged private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Iterator_View => Stable.List,
Aggregate => (Empty => Empty,
Add_Unnamed => Append),
Stable_Properties => (Length,
Tampering_With_Cursors_Prohibited,
Tampering_With_Elements_Prohibited),
Default_Initial_Condition =>
Length (List) = 0 and then
(not Tampering_With_Cursors_Prohibited (List)) and then
(not Tampering_With_Elements_Prohibited (List)),
Preelaborable_Initialization ;
7/5type Cursor is private
with Preelaborable_Initialization ;
8/2Empty_List : constant List;
9/2No_Element : constant Cursor;
9.1/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
9.2/5function Has_Element (Container : List; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
9.3/3package List_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
10/2function "=" (Left, Right : List) return Boolean;
10.1/5function Tampering_With_Cursors_Prohibited
(Container : List) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
10.2/5function Tampering_With_Elements_Prohibited
(Container : List) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
10.3/5function Empty return List
is (Empty_List)
with Post =>
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
11/5function Length (Container : List) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
12/5function Is_Empty (Container : List) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Length (Container) = 0);
13/5procedure Clear (Container : in out List)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = 0;
14/5function Element (Position : Cursor) return Element_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Element_Type;
14.1/5function Element (Container : List;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
15/5procedure Replace_Element (Container : in out List;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
16/5procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
16.1/5procedure Query_Element
(Container : in List;
Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
17/5procedure Update_Element
(Container : in out List;
Position : in Cursor;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
17.1/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
17.2/5type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
17.3/5function Constant_Reference (Container : aliased in List;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Container, Position) or else
raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
17.4/5function Reference (Container : aliased in out List;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Container, Position) or else
raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
17.5/5procedure Assign (Target : in out List; Source : in List)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target);
17.6/5function Copy (Source : List)
return List
with Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result);
18/5procedure Move (Target : in out List;
Source : in out List)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Length (Target) = Length (Source'Old) and then
Length (Source) = 0);
19/5procedure Insert (Container : in out List;
Before : in Cursor;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container);
20/5procedure Insert (Container : in out List;
Before : in Cursor;
New_Item : in Element_Type;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container)
and then Has_Element (Container, Position);
21/5procedure Insert (Container : in out List;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container)
and then Has_Element (Container, Position);
22/5procedure Prepend (Container : in out List;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container);
23/5procedure Append (Container : in out List;
New_Item : in Element_Type;
Count : in Count_Type )
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container);
23.1/5procedure Append (Container : in out List;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => Length (Container)'Old + 1 = Length (Container);
24/5procedure Delete (Container : in out List;
Position : in out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Length (Container)'Old - Count <= Length (Container)
and then Position = No_Element;
25/5procedure Delete_First (Container : in out List;
Count : in Count_Type := 1)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container)'Old - Count <= Length (Container);
26/5procedure Delete_Last (Container : in out List;
Count : in Count_Type := 1)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container)'Old - Count <= Length (Container);
27/5procedure Reverse_Elements (Container : in out List)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error;
28/5procedure Swap (Container : in out List;
I, J : in Cursor)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(I /= No_Element or else Constraint_Error) and then
(J /= No_Element or else Constraint_Error) and then
(Has_Element (Container, I)
or else raise Program_Error) and then
(Has_Element (Container, J)
or else raise Program_Error);
29/5procedure Swap_Links (Container : in out List;
I, J : in Cursor)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(I /= No_Element or else Constraint_Error) and then
(J /= No_Element or else Constraint_Error) and then
(Has_Element (Container, I)
or else raise Program_Error) and then
(Has_Element (Container, J)
or else raise Program_Error);
30/5procedure Splice (Target : in out List;
Before : in Cursor;
Source : in out List)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Target, Before)
or else raise Program_Error) and then
(Target'Has_Same_Storage (Source) or else
Length (Target) <= Count_Type'Last - Length (Source)
or else raise Constraint_Error),
Post => (if not Target'Has_Same_Storage (Source) then
(declare
Result_Length : constant Count_Type :=
Length (Source)'Old + Length (Target)'Old;
begin
Length (Source) = 0 and then
Length (Target) = Result_Length));
31/5procedure Splice (Target : in out List;
Before : in Cursor;
Source : in out List;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Source, Position)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Target, Before)
or else raise Program_Error) and then
(Target'Has_Same_Storage (Source) or else
Length (Target) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Org_Target_Length : constant Count_Type :=
Length (Target)'Old;
Org_Source_Length : constant Count_Type :=
Length (Source)'Old;
begin
(if Target'Has_Same_Storage (Source) then
Position = Position'Old
else
Length (Source) = Org_Source_Length - 1 and then
Length (Target) = Org_Target_Length + 1 and then
Has_Element (Target, Position)));
32/2procedure Splice (Container: in out List;
Before : in Cursor;
Position : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error),
Post => Length (Container) = Length (Container)'Old;
33/5function First (Container : List) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, First'Result)
else First'Result = No_Element);
34/5function First_Element (Container : List)
return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
35/5function Last (Container : List) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, Last'Result)
else Last'Result = No_Element);
36/5function Last_Element (Container : List)
return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
37/5function Next (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then Next'Result = No_Element);
37.1/5function Next (Container : List;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Next'Result = No_Element
elsif Next'Result = No_Element then
Position = Last (Container)
else Has_Element (Container, Next'Result));
38/5function Previous (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then
Previous'Result = No_Element);
38.1/5function Previous (Container : List;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then
Previous'Result = No_Element
elsif Previous'Result = No_Element then
Position = First (Container)
else Has_Element (Container, Previous'Result));
39/5procedure Next (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
39.1/5procedure Next (Container : in List;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
40/5procedure Previous (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
40.1/5procedure Previous (Container : in List;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element then
Has_Element (Container, Position));
41/5function Find (Container : List;
Item : Element_Type;
Position : Cursor := No_Element)
return Cursor
with Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
42/5function Reverse_Find (Container : List;
Item : Element_Type;
Position : Cursor := No_Element)
return Cursor
with Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Reverse_Find'Result /= No_Element
then Has_Element (Container, Reverse_Find'Result));
43/2function Contains (Container : List;
Item : Element_Type) return Boolean;
44/3This paragraph was deleted.
45/5procedure Iterate
(Container : in List;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
46/5procedure Reverse_Iterate
(Container : in List;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
46.1/5function Iterate (Container : in List)
return List_Iterator_Interfaces.Parallel_Reversible_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
46.2/5function Iterate (Container : in List; Start : in Cursor)
return List_Iterator_Interfaces.Reversible_Iterator'Class
with Pre => (Start /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Start)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
47/5generic
with function "<" (Left, Right : Element_Type)
return Boolean is <>;
package Generic_Sorting
with Nonblocking, Global => null is
48/2function Is_Sorted (Container : List) return Boolean;
49/5procedure Sort (Container : in out List)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error;
50/5procedure Merge (Target : in out List;
Source : in out List)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Elements_Prohibited (Source)
or else raise Program_Error) and then
(Length (Target) <= Count_Type'Last - Length (Source)
or else raise Constraint_Error) and then
((Length (Source) = 0 or else
not Target'Has_Same_Storage (Source))
or else raise Constraint_Error),
Post => (declare
Result_Length : constant Count_Type :=
Length (Source)'Old + Length (Target)'Old;
begin
(Length (Source) = 0 and then
Length (Target) = Result_Length));
51/2end Generic_Sorting;
51.1/5package Stable is
51.2/5type List (Base : not null access Doubly_Linked_Lists.List) is
tagged limited private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Stable_Properties => (Length),
Global => null,
Default_Initial_Condition => Length (List) = 0,
Preelaborable_Initialization;
51.3/5type Cursor is private
with Preelaborable_Initialization;
51.4/5Empty_List : constant List;
51.5/5No_Element : constant Cursor;
51.6/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
51.7/5package List_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
51.8/5procedure Assign (Target : in out Doubly_Linked_Lists.List;
Source : in List)
with Post => Length (Source) = Length (Target);
51.9/5function Copy (Source : Doubly_Linked_Lists.List) return List
with Post => Length (Copy'Result) = Length (Source);
51.10/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null, Use_Formal => null,
Default_Initial_Condition => (raise Program_Error);
51.11/5type Reference_Type
(Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null, Use_Formal => null,
Default_Initial_Condition => (raise Program_Error);
51.12/5-- Additional subprograms as described in the text
-- are declared here.
51.13/5private
51.14/5... -- not specified by the language
51.15/5end Stable;
52/2private
53/2... -- not specified by the language
54/2end Ada.Containers.Doubly_Linked_Lists;
The actual function for the generic formal function "=" on Element_Type values is expected to define a reflexive and symmetric relationship and return the same result value each time it is called with a particular pair of values. If it behaves in some other manner, the functions Find, Reverse_Find, and "=" on list values return an unspecified value. The exact arguments and number of calls of this generic formal function by the functions Find, Reverse_Find, and "=" on list values are unspecified.
The type List is used to represent lists. The type List needs finalization (see 7.6).
Empty_List represents the empty List object. It has a length of 0. If an object of type List is not otherwise initialized, it is initialized to the same value as Empty_List.
No_Element represents a cursor that designates no element. If an object of type Cursor is not otherwise initialized, it is initialized to the same value as No_Element.
The primitive "=" operator for type Cursor returns True if both cursors are No_Element, or designate the same element in the same container.
Execution of the default implementation of the Input, Output, Read, or Write attribute of type Cursor raises Program_Error.
List'Write for a List object L writes Length(L) elements of the list to the stream. It may also write additional information about the list.
List'Read reads the representation of a list from the stream, and assigns to Item a list with the same length and elements as was written by List'Write.
[Some operations check for “tampering with cursors” of a container because they depend on the set of elements of the container remaining constant, and others check for “tampering with elements” of a container because they depend on elements of the container not being replaced.] When tampering with cursors is prohibited for a particular list object L, Program_Error is propagated by the finalization of L[, as well as by a call that passes L to certain of the operations of this package, as indicated by the precondition of such an operation]. Similarly, when tampering with elements is prohibited for L, Program_Error is propagated by a call that passes L to certain of the other operations of this package, as indicated by the precondition of such an operation.
Paragraphs 62 through 69 are removed as preconditions now describe these rules.
assignment_statement, because that finalizes the target object as part of the operation, and finalization of an object is already defined as tampering with cursors.
function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
Returns True if Position designates an element, and returns False otherwise.
function Has_Element (Container : List; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if Position designates an element in Container, and returns False otherwise.
function "=" (Left, Right : List) return Boolean;
If Left and Right denote the same list object, then the function returns True. If Left and Right have different lengths, then the function returns False. Otherwise, it compares each element in Left to the corresponding element in Right using the generic formal equality operator. If any such comparison returns False, the function returns False; otherwise, it returns True. Any exception raised during evaluation of element equality is propagated.
function Tampering_With_Cursors_Prohibited
(Container : List) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if tampering with cursors or tampering with elements is currently prohibited for Container, and returns False otherwise.
function Tampering_With_Elements_Prohibited
(Container : List) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Always returns False[, regardless of whether tampering with elements is prohibited].
function Length (Container : List) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
Returns the number of elements in Container.
function Is_Empty (Container : List) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Length (Container) = 0);
Returns True if Container is empty .
procedure Clear (Container : in out List)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = 0;
Removes all the elements from Container.
function Element (Position : Cursor) return Element_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Element_Type;
Element returns the element designated by Position.
function Element (Container : List;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
Element returns the element designated by Position in Container.
procedure Replace_Element (Container : in out List;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Replace_Element assigns the value New_Item to the element designated by Position. For the purposes of determining whether the parameters overlap in a call to Replace_Element, the Container parameter is not considered to overlap with any object [(including itself)].
procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
Query_Element calls Process.all with the element designated by Position as the argument. Tampering with the elements of the list that contains the element designated by Position is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Query_Element
(Container : in List;
Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Query_Element calls Process.all with the element designated by Position as the argument. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Update_Element
(Container : in out List;
Position : in Cursor;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Update_Element calls Process.all with the element designated by Position as the argument. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all shall be unconstrained.
type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
86.2/5type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
The types Constant_Reference_Type and Reference_Type need finalization.
This paragraph was deleted.
function Constant_Reference (Container : aliased in List;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Container, Position) or else
raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read access to an individual element of a list given a cursor.
Constant_Reference returns an object whose discriminant is an access value that designates the element designated by Position. Tampering with the elements of Container is prohibited while the object returned by Constant_Reference exists and has not been finalized.
function Reference (Container : aliased in out List;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Container, Position) or else
raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read and write access to an individual element of a list given a cursor.
Reference returns an object whose discriminant is an access value that designates the element designated by Position. Tampering with the elements of Container is prohibited while the object returned by Reference exists and has not been finalized.
procedure Assign (Target : in out List; Source : in List)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target);
If Target denotes the same object as Source, the operation has no effect. Otherwise, the elements of Source are copied to Target as for an assignment_statement assigning Source to Target.
function Copy (Source : List)
return List
with Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result);
Returns a list whose elements match the elements of Source.
procedure Move (Target : in out List;
Source : in out List)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Length (Target) = Length (Source'Old) and then
Length (Source) = 0);
If Target denotes the same object as Source, then the operation has no effect. Otherwise, the operation is equivalent to Assign (Target, Source) followed by Clear (Source).
procedure Insert (Container : in out List;
Before : in Cursor;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container);
Insert inserts Count copies of New_Item prior to the element designated by Before. If Before equals No_Element, the new elements are inserted after the last node (if any). Any exception raised during allocation of internal storage is propagated, and Container is not modified.
procedure Insert (Container : in out List;
Before : in Cursor;
New_Item : in Element_Type;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container)
and then Has_Element (Container, Position);
Insert allocates Count copies of New_Item, and inserts them prior to the element designated by Before. If Before equals No_Element, the new elements are inserted after the last element (if any). Position designates the first newly-inserted element, or if Count equals 0, then Position is assigned the value of Before. Any exception raised during allocation of internal storage is propagated, and Container is not modified.
procedure Insert (Container : in out List;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container)
and then Has_Element (Container, Position);
Insert inserts Count new elements prior to the element designated by Before. If Before equals No_Element, the new elements are inserted after the last node (if any). The new elements are initialized by default (see 3.3.1). Position designates the first newly-inserted element, or if Count equals 0, then Position is assigned the value of Before. Any exception raised during allocation of internal storage is propagated, and Container is not modified.
procedure Prepend (Container : in out List;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container);
Equivalent to Insert (Container, First (Container), New_Item, Count).
procedure Append (Container : in out List;
New_Item : in Element_Type;
Count : in Count_Type )
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - Count
or else raise Constraint_Error),
Post => Length (Container)'Old + Count = Length (Container);
Equivalent to Insert (Container, No_Element, New_Item, Count).
procedure Append (Container : in out List;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => Length (Container)'Old + 1 = Length (Container);
Equivalent to Insert (Container, No_Element, New_Item, 1).
procedure Delete (Container : in out List;
Position : in out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Length (Container)'Old - Count <= Length (Container)
and then Position = No_Element;
Delete removes (from Container) Count elements starting at the element designated by Position (or all of the elements starting at Position if there are fewer than Count elements starting at Position). Finally, Position is set to No_Element.
procedure Delete_First (Container : in out List;
Count : in Count_Type := 1)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container)'Old - Count <= Length (Container);
If Length (Container) <= Count, then Delete_First is equivalent to Clear (Container). Otherwise, it removes the first Count nodes from Container.
procedure Delete_Last (Container : in out List;
Count : in Count_Type := 1)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container)'Old - Count <= Length (Container);
If Length (Container) <= Count, then Delete_Last is equivalent to Clear (Container). Otherwise, it removes the last Count nodes from Container.
procedure Reverse_Elements (Container : in out List)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error;
Reorders the elements of Container in reverse order.
procedure Swap (Container : in out List;
I, J : in Cursor)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(I /= No_Element or else Constraint_Error) and then
(J /= No_Element or else Constraint_Error) and then
(Has_Element (Container, I)
or else raise Program_Error) and then
(Has_Element (Container, J)
or else raise Program_Error);
Swap exchanges the values of the elements designated by I and J.
procedure Swap_Links (Container : in out List;
I, J : in Cursor)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(I /= No_Element or else Constraint_Error) and then
(J /= No_Element or else Constraint_Error) and then
(Has_Element (Container, I)
or else raise Program_Error) and then
(Has_Element (Container, J)
or else raise Program_Error);
Swap_Links exchanges the nodes designated by I and J.
procedure Splice (Target : in out List;
Before : in Cursor;
Source : in out List)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Target, Before)
or else raise Program_Error) and then
(Target'Has_Same_Storage (Source) or else
Length (Target) <= Count_Type'Last - Length (Source)
or else raise Constraint_Error),
Post => (if not Target'Has_Same_Storage (Source) then
(declare
Result_Length : constant Count_Type :=
Length (Source)'Old + Length (Target)'Old;
begin
Length (Source) = 0 and then
Length (Target) = Result_Length));
If Source denotes the same object as Target, the operation has no effect. Otherwise, Splice reorders elements such that they are removed from Source and moved to Target, immediately prior to Before. If Before equals No_Element, the nodes of Source are spliced after the last node of Target.
procedure Splice (Target : in out List;
Before : in Cursor;
Source : in out List;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Source, Position)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Target, Before)
or else raise Program_Error) and then
(Target'Has_Same_Storage (Source) or else
Length (Target) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Org_Target_Length : constant Count_Type :=
Length (Target)'Old;
Org_Source_Length : constant Count_Type :=
Length (Source)'Old;
begin
(if Target'Has_Same_Storage (Source) then
Position = Position'Old
else Length (Source) = Org_Source_Length - 1 and then
Length (Target) = Org_Target_Length + 1 and then
Has_Element (Target, Position)));
If Source denotes the same object as Target, then there is no effect if Position equals Before, else the element designated by Position is moved immediately prior to Before, or, if Before equals No_Element, after the last element. Otherwise, the element designated by Position is removed from Source and moved to Target, immediately prior to Before, or, if Before equals No_Element, after the last element of Target. Position is updated to represent an element in Target.
procedure Splice (Container: in out List;
Before : in Cursor;
Position : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error) and then
(Before = No_Element or else
Has_Element (Container, Before)
or else raise Program_Error),
Post => Length (Container) = Length (Container)'Old;
If Position equals Before there is no effect. Otherwise, the element designated by Position is moved immediately prior to Before, or, if Before equals No_Element, after the last element.
function First (Container : List) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, First'Result)
else First'Result = No_Element);
If Container is empty, First returns No_Element. Otherwise, it returns a cursor that designates the first node in Container.
function First_Element (Container : List)
return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
Equivalent to Element (Container, First_Index (Container)).
function Last (Container : List) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, Last'Result)
else Last'Result = No_Element);
If Container is empty, Last returns No_Element. Otherwise, it returns a cursor that designates the last node in Container.
function Last_Element (Container : List)
return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
Equivalent to Element (Last (Container)).
function Next (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then Next'Result = No_Element);
If Position equals No_Element or designates the last element of the container, then Next returns the value No_Element. Otherwise, it returns a cursor that designates the successor of the element designated by Position.
function Next (Container : List;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Next'Result = No_Element
elsif Next'Result = No_Element then
Position = Last (Container)
else Has_Element (Container, Next'Result));
Returns a cursor designating the successor of the element designated by Position in Container.
function Previous (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then
Previous'Result = No_Element);
If Position equals No_Element or designates the first element of the container, then Previous returns the value No_Element. Otherwise, it returns a cursor that designates the predecessor of the element designated by Position.
function Previous (Container : List;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then
Previous'Result = No_Element
elsif Previous'Result = No_Element then
Position = First (Container)
else Has_Element (Container, Previous'Result));
Returns a cursor designating the predecessor of the element designated by Position in Container, if any.
procedure Next (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
Equivalent to Position := Next (Position).
procedure Next (Container : in List;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
Equivalent to Position := Next (Container, Position).
procedure Previous (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
Equivalent to Position := Previous (Position).
procedure Previous (Container : in List;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
Equivalent to Position := Previous (Container, Position).
function Find (Container : List;
Item : Element_Type;
Position : Cursor := No_Element)
return Cursor
with Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
Find searches the elements of Container for an element equal to Item (using the generic formal equality operator). The search starts at the element designated by Position, or at the first element if Position equals No_Element. It proceeds towards Last (Container). If no equal element is found, then Find returns No_Element. Otherwise, it returns a cursor designating the first equal element encountered.
function Reverse_Find (Container : List;
Item : Element_Type;
Position : Cursor := No_Element)
return Cursor
with Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Reverse_Find'Result /= No_Element
then Has_Element (Container, Reverse_Find'Result));
Find searches the elements of Container for an element equal to Item (using the generic formal equality operator). The search starts at the element designated by Position, or at the last element if Position equals No_Element. It proceeds towards First (Container). If no equal element is found, then Reverse_Find returns No_Element. Otherwise, it returns a cursor designating the first equal element encountered.
function Contains (Container : List;
Item : Element_Type) return Boolean;
Equivalent to Find (Container, Item) /= No_Element.
Paragraphs 139 and 140 were moved above.
procedure Iterate
(Container : in List;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
Iterate calls Process.all with a cursor that designates each node in Container, starting with the first node and moving the cursor as per the Next function. Tampering with the cursors of Container is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
procedure Reverse_Iterate
(Container : in List;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
Iterates over the nodes in Container as per procedure Iterate, except that elements are traversed in reverse order, starting with the last node and moving the cursor as per the Previous function.
function Iterate (Container : in List)
return List_Iterator_Interfaces.Parallel_Reversible_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each node in Container, starting with the first node and moving the cursor as per the Next function when used as a forward iterator, and starting with the last node and moving the cursor as per the Previous function when used as a reverse iterator, and processing all nodes concurrently when used as a parallel iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
function Iterate (Container : in List; Start : in Cursor)
return List_Iterator_Interfaces.Reversible_Iterator'Class
with Pre => (Start /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Start)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns a reversible iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each node in Container, starting with the node designated by Start and moving the cursor as per the Next function when used as a forward iterator, or moving the cursor as per the Previous function when used as a reverse iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
exit when Cur = Stop;
The actual function for the generic formal function "<" of Generic_Sorting is expected to return the same value each time it is called with a particular pair of element values. It should define a strict weak ordering relationship (see A.18); it should not modify Container. If the actual for "<" behaves in some other manner, the behavior of the subprograms of Generic_Sorting are unspecified. The number of times the subprograms of Generic_Sorting call "<" is unspecified.
function Is_Sorted (Container : List) return Boolean;
Returns True if the elements are sorted smallest first as determined by the generic formal "<" operator; otherwise, Is_Sorted returns False. Any exception raised during evaluation of "<" is propagated.
procedure Sort (Container : in out List)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error;
Reorders the nodes of Container such that the elements are sorted smallest first as determined by the generic formal "<" operator provided. The sort is stable. Any exception raised during evaluation of "<" is propagated.
procedure Merge (Target : in out List;
Source : in out List)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Elements_Prohibited (Source)
or else raise Program_Error) and then
(Length (Target) <= Count_Type'Last - Length (Source)
or else raise Constraint_Error) and then
((Length (Source) = 0 or else
not Target'Has_Same_Storage (Source))
or else raise Constraint_Error),
Post => (declare
Result_Length : constant Count_Type :=
Length (Source)'Old + Length (Target)'Old;
begin
(Length (Source) = 0 and then
Length (Target) = Result_Length));
Merge removes elements from Source and inserts them into Target; afterwards, Target contains the union of the elements that were initially in Source and Target; Source is left empty. If Target and Source are initially sorted smallest first, then Target is ordered smallest first as determined by the generic formal "<" operator; otherwise, the order of elements in Target is unspecified. Any exception raised during evaluation of "<" is propagated.
The nested package Doubly_Linked_Lists.Stable provides a type Stable.List that represents a stable list, which is one that cannot grow and shrink. Such a list can be created by calling the Copy function, or by establishing a stabilized view of an ordinary list.
The subprograms of package Containers.Doubly_Linked_Lists that have a parameter or result of type List are included in the nested package Stable with the same specification, except that the following are omitted:
Tampering_With_Cursors_Prohibited, Tampering_With_Elements_Prohibited, Assign, Move, Insert, Append, Prepend, Clear, Delete, Delete_First, Delete_Last, Splice, Swap_Links, and Reverse_Elements
The operations of this package are equivalent to those for ordinary lists, except that the calls to Tampering_With_Cursors_Prohibited and Tampering_With_Elements_Prohibited that occur in preconditions are replaced by False, and any that occur in postconditions are replaced by True.
If a stable list is declared with the Base discriminant designating a pre-existing ordinary list, the stable list represents a stabilized view of the underlying ordinary list, and any operation on the stable list is reflected on the underlying ordinary list. While a stabilized view exists, any operation that tampers with elements performed on the underlying list is prohibited. The finalization of a stable list that provides such a view removes this restriction on the underlying ordinary list [(though some other restriction can exist due to other concurrent iterations or stabilized views)].
If a stable list is declared without specifying Base, the object is necessarily initialized. The initializing expression of the stable list, [typically a call on Copy], determines the Length of the list. The Length of a stable list never changes after initialization.
Bounded (Run-Time) Errors
152/2Calling Merge in an instance of Generic_Sorting with either Source or Target not ordered smallest first using the provided generic formal "<" operator is a bounded error. Either Program_Error is raised after Target is updated as described for Merge, or the operation works as defined.
It is a bounded error for the actual function associated with a generic formal subprogram, when called as part of an operation of this package, to tamper with elements of any List parameter of the operation. Either Program_Error is raised, or the operation works as defined on the value of the List either prior to, or subsequent to, some or all of the modifications to the List.
It is a bounded error to call any subprogram declared in the visible part of Containers.Doubly_Linked_Lists when the associated container has been finalized. If the operation takes Container as an in out parameter, then it raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for an empty container, or it raises Constraint_Error or Program_Error.
Erroneous Execution
153/2A Cursor value is invalid if any of the following have occurred since it was created:
- The list that contains the element it designates has been finalized;
- The list that contains the element it designates has been used as the Target of a call to Assign, or as the target of an
assignment_statement; 155/2 - [The list that contains the element it designates has been used as the Source or Target of a call to Move;] or
- The element it designates has been removed from the list that previously contained the element.
The result of "=" or Has_Element is unspecified if it is called with an invalid cursor parameter. Execution is erroneous if any other subprogram declared in Containers.Doubly_Linked_Lists is called with an invalid cursor parameter.
Execution is erroneous if the list associated with the result of a call to Reference or Constant_Reference is finalized before the result object returned by the call to Reference or Constant_Reference is finalized.
Implementation Requirements
158/5No storage associated with a doubly-linked list object shall be lost upon assignment or scope exit.
The execution of an assignment_statement for a list shall have the effect of copying the elements from the source list object to the target list object and changing the length of the target object to that of the source object.
Implementation Advice
160/2Containers.Doubly_Linked_Lists should be implemented similarly to a linked list. In particular, if N is the length of a list, then the worst-case time complexity of Element, Insert with Count=1, and Delete with Count=1 should be O(log N).
The worst-case time complexity of a call on procedure Sort of an instance of Containers.Doubly_Linked_Lists.Generic_Sorting should be O(N**2), and the average time complexity should be better than O(N**2).
Move should not copy elements, and should minimize copying of internal data structures.
If an exception is propagated from a list operation, no storage should be lost, nor any elements removed from a list unless specified by the operation.
Extensions to Ada 95
Inconsistencies With Ada 2005
Incompatibilities With Ada 2005
use_clause, and an entity E with the same defining_identifier as a new entity in Containers.Doubly_Linked_Lists is defined in a package that is also referenced in a use_clause, the entity E may no longer be use-visible, resulting in errors. This should be rare and is easily fixed if it does occur. Extensions to Ada 2005
Wording Changes from Ada 2005
Inconsistencies With Ada 2012
Incompatibilities With Ada 2012
Extensions to Ada 2012
aggregate syntax can be used to create Lists.Wording Changes from Ada 2012
A.18.4 Maps
1/2The language-defined generic packages Containers.Hashed_Maps and Containers.Ordered_Maps provide private types Map and Cursor, and a set of operations for each type. A map container allows an arbitrary type to be used as a key to find the element associated with that key. A hashed map uses a hash function to organize the keys, while an ordered map orders the keys per a specified relation.
This subclause describes the declarations that are common to both kinds of maps. See A.18.5 for a description of the semantics specific to Containers.Hashed_Maps and A.18.6 for a description of the semantics specific to Containers.Ordered_Maps.
Static Semantics
3/2The actual function for the generic formal function "=" on Element_Type values is expected to define a reflexive and symmetric relationship and return the same result value each time it is called with a particular pair of values. If it behaves in some other manner, the function "=" on map values returns an unspecified value. The exact arguments and number of calls of this generic formal function by the function "=" on map values are unspecified.
The type Map is used to represent maps. The type Map needs finalization (see 7.6).
A map contains pairs of keys and elements, called nodes. Map cursors designate nodes, but also can be thought of as designating an element (the element contained in the node) for consistency with the other containers. There exists an equivalence relation on keys, whose definition is different for hashed maps and ordered maps. A map never contains two or more nodes with equivalent keys. The length of a map is the number of nodes it contains.
Each nonempty map has two particular nodes called the first node and the last node (which may be the same). Each node except for the last node has a successor node. If there are no other intervening operations, starting with the first node and repeatedly going to the successor node will visit each node in the map exactly once until the last node is reached. The exact definition of these terms is different for hashed maps and ordered maps.
[Some operations check for “tampering with cursors” of a container because they depend on the set of elements of the container remaining constant, and others check for “tampering with elements” of a container because they depend on elements of the container not being replaced.] When tampering with cursors is prohibited for a particular map object M, Program_Error is propagated by the finalization of M[, as well as by a call that passes M to certain of the operations of this package, as indicated by the precondition of such an operation]. Similarly, when tampering with elements is prohibited for M, Program_Error is propagated by a call that passes M to certain of the other operations of this package, as indicated by the precondition of such an operation.
Paragraphs 8 through 15 are removed as preconditions now describe these rules.
assignment_statement, because that finalizes the target object as part of the operation, and finalization of an object is already defined as tampering with cursors.
Empty_Map represents the empty Map object. It has a length of 0. If an object of type Map is not otherwise initialized, it is initialized to the same value as Empty_Map.
No_Element represents a cursor that designates no node. If an object of type Cursor is not otherwise initialized, it is initialized to the same value as No_Element.
The primitive "=" operator for type Cursor returns True if both cursors are No_Element, or designate the same element in the same container.
Execution of the default implementation of the Input, Output, Read, or Write attribute of type Cursor raises Program_Error.
Map'Write for a Map object M writes Length(M) elements of the map to the stream. It may also write additional information about the map.
Map'Read reads the representation of a map from the stream, and assigns to Item a map with the same length and elements as was written by Map'Write.
function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
Returns True if Position designates an element, and returns False otherwise.
function Has_Element (Container : Map; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if Position designates an element in Container, and returns False otherwise.
function "=" (Left, Right : Map) return Boolean;
If Left and Right denote the same map object, then the function returns True. If Left and Right have different lengths, then the function returns False. Otherwise, for each key K in Left, the function returns False if:
- a key equivalent to K is not present in Right; or
- the element associated with K in Left is not equal to the element associated with K in Right (using the generic formal equality operator for elements).
If the function has not returned a result after checking all of the keys, it returns True. Any exception raised during evaluation of key equivalence or element equality is propagated.
function Tampering_With_Cursors_Prohibited
(Container : Map) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if tampering with cursors or tampering with elements is currently prohibited for Container, and returns False otherwise.
function Tampering_With_Elements_Prohibited
(Container : Map) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Always returns False[, regardless of whether tampering with elements is prohibited].
function Length (Container : Map) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
Returns the number of nodes in Container.
function Is_Empty (Container : Map) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Length (Container) = 0);
Returns True if Container is empty .
procedure Clear (Container : in out Map)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = 0;
Removes all the nodes from Container.
function Key (Position : Cursor) return Key_Type
with Pre => Position /= No_Element
or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Key_Type;
Key returns the key component of the node designated by Position.
function Key (Container : Map;
Position : Cursor) return Key_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Key_Type;
Key returns the key component of the node designated by Position.
function Element (Position : Cursor) return Element_Type
with Pre => Position /= No_Element
or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Element_Type;
Element returns the element component of the node designated by Position.
function Element (Container : Map;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
Element returns the element component of the node designated by Position.
procedure Replace_Element (Container : in out Map;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Replace_Element assigns New_Item to the element of the node designated by Position. For the purposes of determining whether the parameters overlap in a call to Replace_Element, the Container parameter is not considered to overlap with any object [(including itself)].
procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Key : in Key_Type;
Element : in Element_Type))
with Pre => Position /= No_Element
or else raise Constraint_Error,
Global => in all;
Query_Element calls Process.all with the key and element from the node designated by Position as the arguments. Tampering with the elements of the map that contains the element designated by Position is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Query_Element
(Container : in Map;
Position : in Cursor;
Process : not null access procedure (Key : in Key_Type;
Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Query_Element calls Process.all with the key and element from the node designated by Position as the arguments. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Update_Element
(Container : in out Map;
Position : in Cursor;
Process : not null access procedure (Key : in Key_Type;
Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Update_Element calls Process.all with the key and element from the node designated by Position as the arguments. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all shall be unconstrained.
type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global =>in out synchronized,
Default_Initial_Condition => (raise Program_Error);
41.2/5type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
The types Constant_Reference_Type and Reference_Type need finalization.
This paragraph was deleted.
function Constant_Reference (Container : aliased in Map;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read access to an individual element of a Map given a cursor.
Constant_Reference returns an object whose discriminant is an access value that designates the element designated by Position. Tampering with the elements of Container is prohibited while the object returned by Constant_Reference exists and has not been finalized.
function Reference (Container : aliased in out Map;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read and write access to an individual element of a Map given a cursor.
Reference returns an object whose discriminant is an access value that designates the element designated by Position. Tampering with the elements of Container is prohibited while the object returned by Reference exists and has not been finalized.
function Constant_Reference (Container : aliased in Map;
Key : in Key_Type)
return Constant_Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read access to an individual element of a map given a key value.
Equivalent to Constant_Reference (Container, Find (Container, Key)).
function Reference (Container : aliased in out Map;
Key : in Key_Type)
return Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read and write access to an individual element of a map given a key value.
Equivalent to Reference (Container, Find (Container, Key)).
procedure Assign (Target : in out Map; Source : in Map)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target);
If Target denotes the same object as Source, the operation has no effect. Otherwise, the key/element pairs of Source are copied to Target as for an assignment_statement assigning Source to Target.
procedure Move (Target : in out Map;
Source : in out Map)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Length (Target) = Length (Source'Old) and then
Length (Source) = 0);
If Target denotes the same object as Source, then the operation has no effect. Otherwise, the operation is equivalent to Assign (Target, Source) followed by Clear (Source).
procedure Insert (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length));
Insert checks if a node with a key equivalent to Key is already present in Container. If a match is found, Inserted is set to False and Position designates the element with the matching key. Otherwise, Insert allocates a new node, initializes it to Key and New_Item, and adds it to Container; Inserted is set to True and Position designates the newly-inserted node. Any exception raised during allocation is propagated and Container is not modified.
procedure Insert (Container : in out Map;
Key : in Key_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length));
Insert inserts Key into Container as per the five-parameter Insert, with the difference that an element initialized by default (see 3.3.1) is inserted.
procedure Insert (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => Length (Container) = Length (Container)'Old + 1;
Insert inserts Key and New_Item into Container as per the five-parameter Insert, with the difference that if a node with a key equivalent to Key is already in the map, then Constraint_Error is propagated.
declare
Inserted : Boolean; C : Cursor;
begin
Insert (Container, Key, New_Item, C, Inserted);
if not Inserted then
raise Constraint_Error;
end if;
end;
procedure Include (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length | Original_Length + 1);
Include inserts Key and New_Item into Container as per the five-parameter Insert, with the difference that if a node with a key equivalent to Key is already in the map, then this operation assigns Key and New_Item to the matching node. Any exception raised during assignment is propagated.
declare
C : Cursor := Find (Container, Key);
begin
if C = No_Element then
Insert (Container, Key, New_Item);
else
Replace (Container, Key, New_Item);
end if;
end;
procedure Replace (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old;
Replace checks if a node with a key equivalent to Key is present in Container. If a match is found, Replace assigns Key and New_Item to the matching node; otherwise, Constraint_Error is propagated.
procedure Exclude (Container : in out Map;
Key : in Key_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length - 1 | Original_Length);
Exclude checks if a node with a key equivalent to Key is present in Container. If a match is found, Exclude removes the node from the map.
procedure Delete (Container : in out Map;
Key : in Key_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old - 1;
Delete checks if a node with a key equivalent to Key is present in Container. If a match is found, Delete removes the node from the map; otherwise, Constraint_Error is propagated.
procedure Delete (Container : in out Map;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Length (Container) = Length (Container)'Old - 1 and then
Position = No_Element;
Delete removes the node designated by Position from the map.
function First (Container : Map) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, First'Result)
else First'Result = No_Element);
If Length (Container) = 0, then First returns No_Element. Otherwise, First returns a cursor that designates the first node in Container.
function Next (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then Next'Result = No_Element);
Returns a cursor that designates the successor of the node designated by Position. If Position designates the last node, then No_Element is returned. If Position equals No_Element, then No_Element is returned.
function Next (Container : Map;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Next'Result = No_Element
elsif Next'Result = No_Element then
Position = Last (Container)
else Has_Element (Container, Next'Result));
Returns a cursor designating the successor of the node designated by Position in Container.
procedure Next (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
Equivalent to Position := Next (Position).
procedure Next (Container : in Map;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
Equivalent to Position := Next (Container, Position).
function Find (Container : Map;
Key : Key_Type) return Cursor
with Post => (if Find'Result = No_Element
then Has_Element (Container, Find'Result));
If Length (Container) equals 0, then Find returns No_Element. Otherwise, Find checks if a node with a key equivalent to Key is present in Container. If a match is found, a cursor designating the matching node is returned; otherwise, No_Element is returned.
function Element (Container : Map;
Key : Key_Type) return Element_Type;
Equivalent to Element (Find (Container, Key)).
function Contains (Container : Map;
Key : Key_Type) return Boolean;
Equivalent to Find (Container, Key) /= No_Element.
Paragraphs 72 and 73 were moved above.
procedure Iterate
(Container : in Map;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
Iterate calls Process.all with a cursor that designates each node in Container, starting with the first node and moving the cursor according to the successor relation. Tampering with the cursors of Container is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
The nested package Stable provides a type Stable.Map that represents a stable map, which is one that cannot grow and shrink. Such a map can be created by calling the Copy function, or by establishing a stabilized view of an ordinary map.
The subprograms of the map package that have a parameter or result of type Map are included in the nested package Stable with the same specification, except that the following are omitted:
Tampering_With_Cursors_Prohibited, Tampering_With_Elements_Prohibited, Assign, Move, Insert, Include, Clear, Delete, Exclude, (for Ordered_Maps) Delete_First and Delete_Last, and (for Hashed_Maps) Reserve_Capacity
The operations of this package are equivalent to those for ordinary maps, except that the calls to Tampering_With_Cursors_Prohibited and Tampering_With_Elements_Prohibited that occur in preconditions are replaced by False, and any that occur in postconditions are replaced by True.
If a stable map is declared with the Base discriminant designating a pre-existing ordinary map, the stable map represents a stabilized view of the underlying ordinary map, and any operation on the stable map is reflected on the underlying ordinary map. While a stabilized view exists, any operation that tampers with elements performed on the underlying map is prohibited. The finalization of a stable map that provides such a view removes this restriction on the underlying ordinary map [(though some other restriction can exist due to other concurrent iterations or stabilized views)].
If a stable map is declared without specifying Base, the object is necessarily initialized. The initializing expression of the stable map, [typically a call on Copy], determines the Length of the map. The Length of a stable map never changes after initialization.
Bounded (Run-Time) Errors
75.7/3It is a bounded error for the actual function associated with a generic formal subprogram, when called as part of an operation of a map package, to tamper with elements of any map parameter of the operation. Either Program_Error is raised, or the operation works as defined on the value of the map either prior to, or subsequent to, some or all of the modifications to the map.
It is a bounded error to call any subprogram declared in the visible part of a map package when the associated container has been finalized. If the operation takes Container as an in out parameter, then it raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for an empty container, or it raises Constraint_Error or Program_Error.
Erroneous Execution
76/2A Cursor value is invalid if any of the following have occurred since it was created:
- The map that contains the node it designates has been finalized;
- The map that contains the node it designates has been used as the Target of a call to Assign, or as the target of an
assignment_statement; 78/2 - The map that contains the node it designates has been used as the Source or Target of a call to Move; or
- The node it designates has been removed from the map that previously contained the node.
The result of "=" or Has_Element is unspecified if these functions are called with an invalid cursor parameter. Execution is erroneous if any other subprogram declared in Containers.Hashed_Maps or Containers.Ordered_Maps is called with an invalid cursor parameter.
Execution is erroneous if the map associated with the result of a call to Reference or Constant_Reference is finalized before the result object returned by the call to Reference or Constant_Reference is finalized.
Implementation Requirements
81/5No storage associated with a map object shall be lost upon assignment or scope exit.
The execution of an assignment_statement for a map shall have the effect of copying the elements from the source map object to the target map object and changing the length of the target object to that of the source object.
Implementation Advice
83/2Move should not copy elements, and should minimize copying of internal data structures.
If an exception is propagated from a map operation, no storage should be lost, nor any elements removed from a map unless specified by the operation.
Wording Changes from Ada 95
Extensions to Ada 2005
Wording Changes from Ada 2005
Inconsistencies With Ada 2012
Extensions to Ada 2012
Wording Changes from Ada 2012
A.18.5 The Generic Package Containers.Hashed_Maps
Static Semantics
1/2The generic library package Containers.Hashed_Maps has the following declaration:
with Ada.Iterator_Interfaces;
generic
type Key_Type is private;
type Element_Type is private;
with function Hash (Key : Key_Type) return Hash_Type;
with function Equivalent_Keys (Left, Right : Key_Type)
return Boolean;
with function "=" (Left, Right : Element_Type)
return Boolean is <>;
package Ada.Containers.Hashed_Maps
with Preelaborate, Remote_Types,
Nonblocking, Global => in out synchronized is
type Map is tagged private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Iterator_View => Stable.Map,
Aggregate => (Empty => Empty,
Add_Named => Insert),
Stable_Properties => (Length,
Tampering_With_Cursors_Prohibited,
Tampering_With_Elements_Prohibited),
Default_Initial_Condition =>
Length (Map) = 0 and then
(not Tampering_With_Cursors_Prohibited (Map)) and then
(not Tampering_With_Elements_Prohibited (Map)),
Preelaborable_Initialization ;
type Cursor is private
with Preelaborable_Initialization ;
5/2Empty_Map : constant Map;
6/2No_Element : constant Cursor;
6.1/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
6.2/5function Has_Element (Container : Map; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
6.3/5package Map_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
7/2function "=" (Left, Right : Map) return Boolean;
7.1/5function Tampering_With_Cursors_Prohibited
(Container : Map) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
7.2/5function Tampering_With_Elements_Prohibited
(Container : Map) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
7.3/5function Empty (Capacity : Count_Type := implementation-defined)
return Map
with Post =>
Capacity (Empty'Result) >= Capacity and then
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
8/5function Capacity (Container : Map) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
9/5procedure Reserve_Capacity (Container : in out Map;
Capacity : in Count_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Container.Capacity >= Capacity;
10/5function Length (Container : Map) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
11/5function Is_Empty (Container : Map) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Length (Container) = 0);
12/5procedure Clear (Container : in out Map)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Capacity (Container) = Capacity (Container)'Old and then
Length (Container) = 0;
13/5function Key (Position : Cursor) return Key_Type
with Pre => Position /= No_Element
or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Key_Type;
13.1/5function Key (Container : Map;
Position : Cursor) return Key_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Key_Type;
14/5function Element (Position : Cursor) return Element_Type
with Pre => Position /= No_Element
or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Element_Type;
14.1/5function Element (Container : Map;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
15/5procedure Replace_Element (Container : in out Map;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
16/5procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Key : in Key_Type;
Element : in Element_Type))
with Pre => Position /= No_Element
or else raise Constraint_Error,
Global => in all;
16.1/5procedure Query_Element
(Container : in Map;
Position : in Cursor;
Process : not null access procedure (Key : in Key_Type;
Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
17/5procedure Update_Element
(Container : in out Map;
Position : in Cursor;
Process : not null access procedure
(Key : in Key_Type;
Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
17.1/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
17.2/5type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
17.3/5function Constant_Reference (Container : aliased in Map;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
17.4/5function Reference (Container : aliased in out Map;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
17.5/5function Constant_Reference (Container : aliased in Map;
Key : in Key_Type)
return Constant_Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
17.6/5function Reference (Container : aliased in out Map;
Key : in Key_Type)
return Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
17.7/5procedure Assign (Target : in out Map; Source : in Map)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target) and then
Capacity (Target) >= Length (Source);
17.8/5function Copy (Source : Map; Capacity : Count_Type := 0)
return Map
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result) and then
Copy'Result.Capacity = (if Capacity = 0 then
Length (Source) else Capacity);
18/5procedure Move (Target : in out Map;
Source : in out Map)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Length (Target) = Length (Source'Old) and then
Length (Source) = 0);
19/5procedure Insert (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length)) and then
Capacity (Container) >= Length (Container);
20/5procedure Insert (Container : in out Map;
Key : in Key_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length)) and then
Capacity (Container) >= Length (Container);
21/5procedure Insert (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => Length (Container) = Length (Container)'Old + 1 and then
Capacity (Container) >= Length (Container);
22/5procedure Include (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length | Original_Length + 1) and then
Capacity (Container) >= Length (Container);
23/5procedure Replace (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old;
24/5procedure Exclude (Container : in out Map;
Key : in Key_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length - 1 | Original_Length);
25/5procedure Delete (Container : in out Map;
Key : in Key_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old - 1;
26/5procedure Delete (Container : in out Map;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Length (Container) = Length (Container)'Old - 1 and then
Position = No_Element;
27/5function First (Container : Map) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, First'Result)
else First'Result = No_Element);
28/5function Next (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then Next'Result = No_Element);
28.1/5function Next (Container : Map;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Next'Result = No_Element
elsif Next'Result = No_Element then
Position = Last (Container)
else Has_Element (Container, Next'Result));
29/5procedure Next (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
29.1/5procedure Next (Container : in Map;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
30/5function Find (Container : Map;
Key : Key_Type)
return Cursor
with Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
31/2function Element (Container : Map;
Key : Key_Type)
return Element_Type;
32/2function Contains (Container : Map;
Key : Key_Type) return Boolean;
33/3This paragraph was deleted.
34/5function Equivalent_Keys (Left, Right : Cursor)
return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
35/5function Equivalent_Keys (Left : Cursor;
Right : Key_Type)
return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
36/5function Equivalent_Keys (Left : Key_Type;
Right : Cursor)
return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
37/5procedure Iterate
(Container : in Map;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
37.1/5function Iterate (Container : in Map)
return Map_Iterator_Interfaces.Parallel_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
37.2/5package Stable is
37.3/5type Map (Base : not null access Hashed_Maps.Map) is
tagged limited private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Stable_Properties => (Length),
Global => null,
Default_Initial_Condition => Length (Map) = 0,
Preelaborable_Initialization;
37.4/5type Cursor is private
with Preelaborable_Initialization;
37.5/5Empty_Map : constant Map;
37.6/5No_Element : constant Cursor;
37.7/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
37.8/5package Map_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
37.9/5procedure Assign (Target : in out Hashed_Maps.Map;
Source : in Map)
with Post => Length (Source) = Length (Target);
37.10/5function Copy (Source : Hashed_Maps.Map) return Map
with Post => Length (Copy'Result) = Length (Source);
37.11/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null, Use_Formal => null,
Default_Initial_Condition => (raise Program_Error);
37.12/5type Reference_Type
(Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null, Use_Formal => null,
Default_Initial_Condition => (raise Program_Error);
37.13/5-- Additional subprograms as described in the text
-- are declared here.
37.14/5private
37.15/5... -- not specified by the language
37.16/5end Stable;
38/2private
39/2... -- not specified by the language
40/2end Ada.Containers.Hashed_Maps;
An object of type Map contains an expandable hash table, which is used to provide direct access to nodes. The capacity of an object of type Map is the maximum number of nodes that can be inserted into the hash table prior to it being automatically expanded.
Two keys K1 and K2 are defined to be equivalent if Equivalent_Keys (K1, K2) returns True.
The actual function for the generic formal function Hash is expected to return the same value each time it is called with a particular key value. For any two equivalent key values, the actual for Hash is expected to return the same value. If the actual for Hash behaves in some other manner, the behavior of this package is unspecified. Which subprograms of this package call Hash, and how many times they call it, is unspecified.
The actual function for the generic formal function Equivalent_Keys on Key_Type values is expected to return the same value each time it is called with a particular pair of key values. It should define an equivalence relationship, that is, be reflexive, symmetric, and transitive. If the actual for Equivalent_Keys behaves in some other manner, the behavior of this package is unspecified. Which subprograms of this package call Equivalent_Keys, and how many times they call it, is unspecified.
If the value of a key stored in a node of a map is changed other than by an operation in this package such that at least one of Hash or Equivalent_Keys give different results, the behavior of this package is unspecified.
Key (Map).Some_Component := New_Value;
Which nodes are the first node and the last node of a map, and which node is the successor of a given node, are unspecified, other than the general semantics described in A.18.4.
function Empty (Capacity : Count_Type := implementation-defined)
return Map
with Post =>
Capacity (Empty'Result) >= Capacity and then
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
Returns an empty map.
function Capacity (Container : Map) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
Returns the capacity of Container.
procedure Reserve_Capacity (Container : in out Map;
Capacity : in Count_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Container.Capacity >= Capacity;
Reserve_Capacity allocates a new hash table such that the length of the resulting map can become at least the value Capacity without requiring an additional call to Reserve_Capacity, and is large enough to hold the current length of Container. Reserve_Capacity then rehashes the nodes in Container onto the new hash table. It replaces the old hash table with the new hash table, and then deallocates the old hash table. Any exception raised during allocation is propagated and Container is not modified.
This paragraph was deleted.
procedure Clear (Container : in out Map)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Capacity (Container) = Capacity (Container)'Old and then
Length (Container) = 0;
In addition to the semantics described in A.18.4, Clear does not affect the capacity of Container.
procedure Assign (Target : in out Map; Source : in Map)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target) and then
Capacity (Target) >= Length (Source);
In addition to the semantics described in A.18.4, if the length of Source is greater than the capacity of Target, Reserve_Capacity (Target, Length (Source)) is called before assigning any elements.
function Copy (Source : Map; Capacity : Count_Type := 0)
return Map
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result) and then
Copy'Result.Capacity = (if Capacity = 0 then
Length (Source) else Capacity);
Returns a map whose keys and elements are initialized from the keys and elements of Source.
procedure Move (Target : in out Map;
Source : in out Map);
procedure Insert (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length)) and then
Capacity (Container) >= Length (Container);
In addition to the semantics described in A.18.4, if Length (Container) equals Capacity (Container), then Insert first calls Reserve_Capacity to increase the capacity of Container to some larger value.
procedure Exclude (Container : in out Map;
Key : in Key_Type);
procedure Delete (Container : in out Map;
Key : in Key_Type);
function First (Container : Map) return Cursor;
function Next (Position : Cursor) return Cursor;
function Find (Container : Map;
Key : Key_Type) return Cursor;
function Equivalent_Keys (Left, Right : Cursor)
return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
Equivalent to Equivalent_Keys (Key (Left), Key (Right)).
function Equivalent_Keys (Left : Cursor;
Right : Key_Type) return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Equivalent_Keys (Key (Left), Right).
function Equivalent_Keys (Left : Key_Type;
Right : Cursor) return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Equivalent_Keys (Left, Key (Right)).
function Iterate (Container : in Map)
return Map_Iterator_Interfaces.Parallel_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each node in Container, starting with the first node and moving the cursor according to the successor relation when used as a forward iterator, and processing all nodes concurrently when used as a parallel iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
Implementation Advice
62/2If N is the length of a map, the average time complexity of the subprograms Element, Insert, Include, Replace, Delete, Exclude, and Find that take a key parameter should be O(log N). The average time complexity of the subprograms that take a cursor parameter should be O(1). The average time complexity of Reserve_Capacity should be O(N).
Extensions to Ada 95
Incompatibilities With Ada 2005
use_clause, and an entity E with the same defining_identifier as a new entity in Containers.Hashed_Maps is defined in a package that is also referenced in a use_clause, the entity E may no longer be use-visible, resulting in errors. This should be rare and is easily fixed if it does occur. Extensions to Ada 2005
Wording Changes from Ada 2005
Incompatibilities With Ada 2012
Extensions to Ada 2012
aggregate syntax can be used to create Maps.Wording Changes from Ada 2012
A.18.6 The Generic Package Containers.Ordered_Maps
Static Semantics
1/2The generic library package Containers.Ordered_Maps has the following declaration:
with Ada.Iterator_Interfaces;
generic
type Key_Type is private;
type Element_Type is private;
with function "<" (Left, Right : Key_Type) return Boolean is <>;
with function "=" (Left, Right : Element_Type) return Boolean is <>;
package Ada.Containers.Ordered_Maps
with Preelaborate, Remote_Types,
Nonblocking, Global => in out synchronized is
function Equivalent_Keys (Left, Right : Key_Type) return Boolean
is (not ((Left < Right) or (Right < Left)));
4/5type Map is tagged private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Iterator_View => Stable.Map,
Aggregate => (Empty => Empty,
Add_Named => Insert),
Stable_Properties => (Length,
Tampering_With_Cursors_Prohibited,
Tampering_With_Elements_Prohibited),
Default_Initial_Condition =>
Length (Map) = 0 and then
(not Tampering_With_Cursors_Prohibited (Map)) and then
(not Tampering_With_Elements_Prohibited (Map)),
Preelaborable_Initialization ;
5/5type Cursor is private
with Preelaborable_Initialization ;
6/2Empty_Map : constant Map;
7/2No_Element : constant Cursor;
7.1/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
7.2/5function Has_Element (Container : Map; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
7.3/5package Map_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
8/2function "=" (Left, Right : Map) return Boolean;
8.1/5function Tampering_With_Cursors_Prohibited
(Container : Map) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
8.2/5function Tampering_With_Elements_Prohibited
(Container : Map) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
8.3/5function Empty return Map
is (Empty_Map)
with Post =>
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
9/5function Length (Container : Map) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
10/5function Is_Empty (Container : Map) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Length (Container) = 0);
11/5procedure Clear (Container : in out Map)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = 0;
12/5function Key (Position : Cursor) return Key_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Key_Type;
12.1/5function Key (Container : Map;
Position : Cursor) return Key_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Key_Type;
13/5function Element (Position : Cursor) return Element_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Nonblocking, Global => null, Use_Formal => Element_Type;
13.1/5function Element (Container : Map;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
14/5procedure Replace_Element (Container : in out Map;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
15/5procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Key : in Key_Type;
Element : in Element_Type))
with Pre => Position /= No_Element
or else raise Constraint_Error,
Global => in all;
15.1/5procedure Query_Element
(Container : in Map;
Position : in Cursor;
Process : not null access procedure (Key : in Key_Type;
Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
16/5procedure Update_Element
(Container : in out Map;
Position : in Cursor;
Process : not null access procedure
(Key : in Key_Type;
Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
16.1/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
16.2/5type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
16.3/5function Constant_Reference (Container : aliased in Map;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
16.4/5function Reference (Container : aliased in out Map;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
16.5/5function Constant_Reference (Container : aliased in Map;
Key : in Key_Type)
return Constant_Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
16.6/5function Reference (Container : aliased in out Map;
Key : in Key_Type)
return Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
16.7/5procedure Assign (Target : in out Map; Source : in Map)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target);
16.8/5function Copy (Source : Map)
return Map
with Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result);
17/5procedure Move (Target : in out Map;
Source : in out Map)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Length (Target) = Length (Source'Old) and then
Length (Source) = 0);
18/5procedure Insert (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length));
19/5procedure Insert (Container : in out Map;
Key : in Key_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length));
20/5procedure Insert (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => Length (Container) = Length (Container)'Old + 1;
21/5procedure Include (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length | Original_Length + 1);
22/5procedure Replace (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old;
23/5procedure Exclude (Container : in out Map;
Key : in Key_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length - 1 | Original_Length);
24/5procedure Delete (Container : in out Map;
Key : in Key_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old - 1;
25/5procedure Delete (Container : in out Map;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Length (Container) = Length (Container)'Old - 1 and then
Position = No_Element;
26/5procedure Delete_First (Container : in out Map)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
(if Original_Length = 0 then Length (Container) = 0
else Length (Container) = Original_Length - 1));
27/5procedure Delete_Last (Container : in out Map)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
(if Original_Length = 0 then Length (Container) = 0
else Length (Container) = Original_Length - 1));
28/5function First (Container : Map) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, First'Result)
else First'Result = No_Element);
29/5function First_Element (Container : Map) return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
30/5function First_Key (Container : Map) return Key_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
31/5function Last (Container : Map) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, Last'Result)
else Last'Result = No_Element);
32/5function Last_Element (Container : Map) return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
33/5function Last_Key (Container : Map) return Key_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
34/5function Next (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then Next'Result = No_Element);
34.1/5function Next (Container : Map;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Next'Result = No_Element
elsif Next'Result = No_Element then
Position = Last (Container)
else Has_Element (Container, Next'Result));
35/5procedure Next (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
35.1/5procedure Next (Container : in Map;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
36/5function Previous (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then
Previous'Result = No_Element);
36.1/5function Previous (Container : Map;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then
Previous'Result = No_Element
elsif Previous'Result = No_Element then
Position = First (Container)
else Has_Element (Container, Previous'Result));
37/5procedure Previous (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
37.1/5procedure Previous (Container : in Map;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
38/5function Find (Container : Map;
Key : Key_Type) return Cursor
with Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
39/2function Element (Container : Map;
Key : Key_Type) return Element_Type;
40/5function Floor (Container : Map;
Key : Key_Type) return Cursor
with Post => (if Floor'Result /= No_Element
then Has_Element (Container, Floor'Result));
41/5function Ceiling (Container : Map;
Key : Key_Type) return Cursor
with Post => (if Ceiling'Result /= No_Element
then Has_Element (Container, Ceiling'Result));
42/2function Contains (Container : Map;
Key : Key_Type) return Boolean;
43/3This paragraph was deleted.
44/5function "<" (Left, Right : Cursor) return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
45/5function ">" (Left, Right : Cursor) return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
46/5function "<" (Left : Cursor; Right : Key_Type) return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
47/5function ">" (Left : Cursor; Right : Key_Type) return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
48/5function "<" (Left : Key_Type; Right : Cursor) return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
49/5function ">" (Left : Key_Type; Right : Cursor) return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
50/5procedure Iterate
(Container : in Map;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
51/5procedure Reverse_Iterate
(Container : in Map;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
51.1/5function Iterate (Container : in Map)
return Map_Iterator_Interfaces.Parallel_Reversible_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
51.2/5function Iterate (Container : in Map; Start : in Cursor)
return Map_Iterator_Interfaces.Reversible_Iterator'Class
with Pre => (Start /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Start)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
51.3/5package Stable is
51.4/5type Map (Base : not null access Ordered_Maps.Map) is
tagged limited private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Stable_Properties => (Length),
Global => null,
Default_Initial_Condition => Length (Map) = 0,
Preelaborable_Initialization;
51.5/5type Cursor is private
with Preelaborable_Initialization;
51.6/5Empty_Map : constant Map;
51.7/5No_Element : constant Cursor;
51.8/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
51.9/5package Map_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
51.10/5procedure Assign (Target : in out Ordered_Maps.Map;
Source : in Map)
with Post => Length (Source) = Length (Target);
51.11/5function Copy (Source : Ordered_Maps.Map) return Map
with Post => Length (Copy'Result) = Length (Source);
51.12/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null, Use_Formal => null,
Default_Initial_Condition => (raise Program_Error);
51.13/5type Reference_Type
(Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null, Use_Formal => null,
Default_Initial_Condition => (raise Program_Error);
51.14/5-- Additional subprograms as described in the text
-- are declared here.
51.15/5private
51.16/5... -- not specified by the language
51.17/5end Stable;
52/2private
53/2... -- not specified by the language
54/2end Ada.Containers.Ordered_Maps;
Two keys K1 and K2 are equivalent if both K1 < K2 and K2 < K1 return False, using the generic formal "<" operator for keys. Function Equivalent_Keys returns True if Left and Right are equivalent, and False otherwise.
The actual function for the generic formal function "<" on Key_Type values is expected to return the same value each time it is called with a particular pair of key values. It should define a strict weak ordering relationship (see A.18). If the actual for "<" behaves in some other manner, the behavior of this package is unspecified. Which subprograms of this package call "<" and how many times they call it, is unspecified.
If the value of a key stored in a map is changed other than by an operation in this package such that at least one of "<" or "=" give different results, the behavior of this package is unspecified.
Key (Map).Some_Component := New_Value;
The first node of a nonempty map is the one whose key is less than the key of all the other nodes in the map. The last node of a nonempty map is the one whose key is greater than the key of all the other elements in the map. The successor of a node is the node with the smallest key that is larger than the key of the given node. The predecessor of a node is the node with the largest key that is smaller than the key of the given node. All comparisons are done using the generic formal "<" operator for keys.
function Copy (Source : Map)
return Map
with Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result);
Returns a map whose keys and elements are initialized from the corresponding keys and elements of Source.
procedure Delete_First (Container : in out Map)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
(if Original_Length = 0 then Length (Container) = 0
else Length (Container) = Original_Length - 1));
If Container is empty, Delete_First has no effect. Otherwise, the node designated by First (Container) is removed from Container. Delete_First tampers with the cursors of Container.
procedure Delete_Last (Container : in out Map)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
(if Original_Length = 0 then Length (Container) = 0
else Length (Container) = Original_Length - 1));
If Container is empty, Delete_Last has no effect. Otherwise, the node designated by Last (Container) is removed from Container. Delete_Last tampers with the cursors of Container.
function First_Element (Container : Map) return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
Equivalent to Element (First (Container)).
function First_Key (Container : Map) return Key_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
Equivalent to Key (First (Container)).
function Last (Container : Map) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, Last'Result)
else Last'Result = No_Element);
Returns a cursor that designates the last node in Container. If Container is empty, returns No_Element.
function Last_Element (Container : Map) return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
Equivalent to Element (Last (Container)).
function Last_Key (Container : Map) return Key_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
Equivalent to Key (Last (Container)).
function Previous (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then
Previous'Result = No_Element);
If Position equals No_Element, then Previous returns No_Element. Otherwise, Previous returns a cursor designating the predecessor node of the one designated by Position. If Position designates the first element, then Previous returns No_Element.
function Previous (Container : Map;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then
Previous'Result = No_Element
elsif Previous'Result = No_Element then
Position = First (Container)
else Has_Element (Container, Previous'Result));
Returns a cursor designating the predecessor of the node designated by Position in Container, if any.
procedure Previous (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
Equivalent to Position := Previous (Position).
procedure Previous (Container : in Map;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
Equivalent to Position := Previous (Container, Position).
function Floor (Container : Map;
Key : Key_Type) return Cursor
with Post => (if Floor'Result /= No_Element
then Has_Element (Container, Floor'Result));
Floor searches for the last node whose key is not greater than Key, using the generic formal "<" operator for keys. If such a node is found, a cursor that designates it is returned. Otherwise, No_Element is returned.
function Ceiling (Container : Map;
Key : Key_Type) return Cursor
with Post => (if Ceiling'Result /= No_Element
then Has_Element (Container, Ceiling'Result));
Ceiling searches for the first node whose key is not less than Key, using the generic formal "<" operator for keys. If such a node is found, a cursor that designates it is returned. Otherwise, No_Element is returned.
function "<" (Left, Right : Cursor) return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
Equivalent to Key (Left) < Key (Right).
function ">" (Left, Right : Cursor) return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
Equivalent to Key (Right) < Key (Left).
function "<" (Left : Cursor; Right : Key_Type) return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Key (Left) < Right.
function ">" (Left : Cursor; Right : Key_Type) return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Right < Key (Left).
function "<" (Left : Key_Type; Right : Cursor) return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Left < Key (Right).
function ">" (Left : Key_Type; Right : Cursor) return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Key (Right) < Left.
procedure Reverse_Iterate
(Container : in Map;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
Iterates over the nodes in Container as per procedure Iterate, with the difference that the nodes are traversed in predecessor order, starting with the last node.
function Iterate (Container : in Map)
return Map_Iterator_Interfaces.Parallel_Reversible_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each node in Container, starting with the first node and moving the cursor according to the successor relation when used as a forward iterator, and starting with the last node and moving the cursor according to the predecessor relation when used as a reverse iterator, and processing all nodes concurrently when used as a parallel iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
function Iterate (Container : in Map; Start : in Cursor)
return Map_Iterator_Interfaces.Reversible_Iterator'Class
with Pre => (Start /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Start)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns a reversible iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each node in Container, starting with the node designated by Start and moving the cursor according to the successor relation when used as a forward iterator, or moving the cursor according to the predecessor relation when used as a reverse iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
exit when Cur = Stop;
Implementation Advice
95/2If N is the length of a map, then the worst-case time complexity of the Element, Insert, Include, Replace, Delete, Exclude, and Find operations that take a key parameter should be O((log N)**2) or better. The worst-case time complexity of the subprograms that take a cursor parameter should be O(1).
Extensions to Ada 95
Incompatibilities With Ada 2005
use_clause, and an entity E with the same defining_identifier as a new entity in Containers.Ordered_Maps is defined in a package that is also referenced in a use_clause, the entity E may no longer be use-visible, resulting in errors. This should be rare and is easily fixed if it does occur. Extensions to Ada 2005
Wording Changes from Ada 2005
Incompatibilities With Ada 2012
Extensions to Ada 2012
aggregate syntax can be used to create Maps.Wording Changes from Ada 2012
A.18.7 Sets
1/2The language-defined generic packages Containers.Hashed_Sets and Containers.Ordered_Sets provide private types Set and Cursor, and a set of operations for each type. A set container allows elements of an arbitrary type to be stored without duplication. A hashed set uses a hash function to organize elements, while an ordered set orders its element per a specified relation.
This subclause describes the declarations that are common to both kinds of sets. See A.18.8 for a description of the semantics specific to Containers.Hashed_Sets and A.18.9 for a description of the semantics specific to Containers.Ordered_Sets.
Static Semantics
3/2The actual function for the generic formal function "=" on Element_Type values is expected to define a reflexive and symmetric relationship and return the same result value each time it is called with a particular pair of values. If it behaves in some other manner, the function "=" on set values returns an unspecified value. The exact arguments and number of calls of this generic formal function by the function "=" on set values are unspecified.
The type Set is used to represent sets. The type Set needs finalization (see 7.6).
A set contains elements. Set cursors designate elements. There exists an equivalence relation on elements, whose definition is different for hashed sets and ordered sets. A set never contains two or more equivalent elements. The length of a set is the number of elements it contains.
Each nonempty set has two particular elements called the first element and the last element (which may be the same). Each element except for the last element has a successor element. If there are no other intervening operations, starting with the first element and repeatedly going to the successor element will visit each element in the set exactly once until the last element is reached. The exact definition of these terms is different for hashed sets and ordered sets.
[Some operations check for “tampering with cursors” of a container because they depend on the set of elements of the container remaining constant and on elements of the container not being replaced.] When tampering with cursors is prohibited for a particular set object S, Program_Error is propagated by the finalization of S[, as well as by a call that passes S to certain of the operations of this package, as indicated by the precondition of such an operation].
Paragraphs 8 through 14 are removed as preconditions now describe these rules.
assignment_statement, because that finalizes the target object as part of the operation, and finalization of an object is already defined as tampering with cursors.
Empty_Set represents the empty Set object. It has a length of 0. If an object of type Set is not otherwise initialized, it is initialized to the same value as Empty_Set.
No_Element represents a cursor that designates no element. If an object of type Cursor is not otherwise initialized, it is initialized to the same value as No_Element.
The primitive "=" operator for type Cursor returns True if both cursors are No_Element, or designate the same element in the same container.
Execution of the default implementation of the Input, Output, Read, or Write attribute of type Cursor raises Program_Error.
Set'Write for a Set object S writes Length(S) elements of the set to the stream. It may also write additional information about the set.
Set'Read reads the representation of a set from the stream, and assigns to Item a set with the same length and elements as was written by Set'Write.
function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
Returns True if Position designates an element, and returns False otherwise.
function Has_Element (Container : Set; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if Position designates an element in Container, and returns False otherwise.
function "=" (Left, Right : Set) return Boolean;
If Left and Right denote the same set object, then the function returns True. If Left and Right have different lengths, then the function returns False. Otherwise, for each element E in Left, the function returns False if an element equal to E (using the generic formal equality operator) is not present in Right. If the function has not returned a result after checking all of the elements, it returns True. Any exception raised during evaluation of element equality is propagated.
function Equivalent_Sets (Left, Right : Set) return Boolean;
If Left and Right denote the same set object, then the function returns True. If Left and Right have different lengths, then the function returns False. Otherwise, for each element E in Left, the function returns False if an element equivalent to E is not present in Right. If the function has not returned a result after checking all of the elements, it returns True. Any exception raised during evaluation of element equivalence is propagated.
function Tampering_With_Cursors_Prohibited
(Container : Set) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if tampering with cursors is currently prohibited for Container, and returns False otherwise.
function To_Set (New_Item : Element_Type) return Set
with Post => Length (To_Set'Result) = 1 and then
not Tampering_with_Cursors_Prohibited (To_Set'Result);
Returns a set containing the single element New_Item.
function Length (Container : Set) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
Returns the number of elements in Container.
function Is_Empty (Container : Set) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Length (Container) = 0);
Returns True if Container is empty .
procedure Clear (Container : in out Set)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = 0;
Removes all the elements from Container.
function Element (Position : Cursor) return Element_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Element_Type;
Element returns the element designated by Position.
function Element (Container : Set;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
Element returns the element designated by Position.
procedure Replace_Element (Container : in out Set;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Replace_Element assigns New_Item to the element designated by Position. Any exception raised by the assignment is propagated. For the purposes of determining whether the parameters overlap in a call to Replace_Element, the Container parameter is not considered to overlap with any object [(including itself)].
procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => Position /= No_Element
or else raise Constraint_Error,
Global => in all;
Query_Element calls Process.all with the element designated by Position as the argument. Tampering with the elements of the set that contains the element designated by Position is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Query_Element
(Container : in Set;
Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Query_Element calls Process.all with the key and element from the node designated by Position as the arguments. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
The type Constant_Reference_Type needs finalization.
This paragraph was deleted.
function Constant_Reference (Container : aliased in Set;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read access to an individual element of a set given a cursor.
Constant_Reference returns an object whose discriminant is an access value that designates the element designated by Position. Tampering with the cursors of Container is prohibited while the object returned by Constant_Reference exists and has not been finalized.
procedure Assign (Target : in out Set; Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target);
If Target denotes the same object as Source, the operation has no effect. Otherwise, the elements of Source are copied to Target as for an assignment_statement assigning Source to Target.
procedure Move (Target : in out Set;
Source : in out Set)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Length (Target) = Length (Source'Old) and then
Length (Source) = 0);
If Target denotes the same object as Source, then the operation has no effect. Otherwise, the operation is equivalent to Assign (Target, Source) followed by Clear (Source).
procedure Insert (Container : in out Set;
New_Item : in Element_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length));
Insert checks if an element equivalent to New_Item is already present in Container. If a match is found, Inserted is set to False and Position designates the matching element. Otherwise, Insert adds New_Item to Container; Inserted is set to True and Position designates the newly-inserted element. Any exception raised during allocation is propagated and Container is not modified.
procedure Insert (Container : in out Set;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => Length (Container) = Length (Container)'Old + 1;
Insert inserts New_Item into Container as per the four-parameter Insert, with the difference that if an element equivalent to New_Item is already in the set, then Constraint_Error is propagated.
declare
Inserted : Boolean; C : Cursor;
begin
Insert (Container, New_Item, C, Inserted);
if not Inserted then
raise Constraint_Error;
end if;
end;
procedure Include (Container : in out Set;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length | Original_Length + 1);
Include inserts New_Item into Container as per the four-parameter Insert, with the difference that if an element equivalent to New_Item is already in the set, then it is replaced. Any exception raised during assignment is propagated.
procedure Replace (Container : in out Set;
New_Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old;
Replace checks if an element equivalent to New_Item is already in the set. If a match is found, that element is replaced with New_Item; otherwise, Constraint_Error is propagated.
procedure Exclude (Container : in out Set;
Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container) in
Original_Length - 1 | Original_Length);
Exclude checks if an element equivalent to Item is present in Container. If a match is found, Exclude removes the element from the set.
procedure Delete (Container : in out Set;
Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old - 1;
Delete checks if an element equivalent to Item is present in Container. If a match is found, Delete removes the element from the set; otherwise, Constraint_Error is propagated.
procedure Delete (Container : in out Set;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Length (Container) = Length (Container)'Old - 1 and then
Position = No_Element;
Delete removes the element designated by Position from the set.
procedure Union (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
Union inserts into Target the elements of Source that are not equivalent to some element already in Target.
function Union (Left, Right : Set) return Set
with Post => Length (Union'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (Union'Result);
Returns a set comprising all of the elements of Left, and the elements of Right that are not equivalent to some element of Left.
procedure Intersection (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
Intersection deletes from Target the elements of Target that are not equivalent to some element of Source.
function Intersection (Left, Right : Set) return Set
with Post => Length (Intersection'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (Intersection'Result);
Returns a set comprising all the elements of Left that are equivalent to the some element of Right.
procedure Difference (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
If Target denotes the same object as Source, then Difference clears Target. Otherwise, it deletes from Target the elements that are equivalent to some element of Source.
function Difference (Left, Right : Set) return Set
with Post => Length (Difference'Result) <= Length (Left) +
Length (Right) and then
not Tampering_With_Cursors_Prohibited (Difference'Result);
Returns a set comprising the elements of Left that are not equivalent to some element of Right.
procedure Symmetric_Difference (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
If Target denotes the same object as Source, then Symmetric_Difference clears Target. Otherwise, it deletes from Target the elements that are equivalent to some element of Source, and inserts into Target the elements of Source that are not equivalent to some element of Target.
function Symmetric_Difference (Left, Right : Set) return Set
with Post => Length (Symmetric_Difference'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (
Symmetric_Difference'Result);
Returns a set comprising the elements of Left that are not equivalent to some element of Right, and the elements of Right that are not equivalent to some element of Left.
function Overlap (Left, Right : Set) return Boolean;
If an element of Left is equivalent to some element of Right, then Overlap returns True. Otherwise, it returns False.
function Is_Subset (Subset : Set;
Of_Set : Set) return Boolean;
If an element of Subset is not equivalent to some element of Of_Set, then Is_Subset returns False. Otherwise, it returns True.
function First (Container : Set) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, First'Result)
else First'Result = No_Element);
If Length (Container) = 0, then First returns No_Element. Otherwise, First returns a cursor that designates the first element in Container.
function Next (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then Next'Result = No_Element);
Returns a cursor that designates the successor of the element designated by Position. If Position designates the last element, then No_Element is returned. If Position equals No_Element, then No_Element is returned.
function Next (Container : Set;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Next'Result = No_Element
elsif Next'Result = No_Element then
Position = Last (Container)
else Has_Element (Container, Next'Result));
Returns a cursor designating the successor of the node designated by Position in Container.
procedure Next (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
Equivalent to Position := Next (Position).
procedure Next (Container : in Set;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
Equivalent to Position := Next (Container, Position).
This paragraph was deleted.
function Find (Container : Set;
Item : Element_Type) return Cursor
with Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
If Length (Container) equals 0, then Find returns No_Element. Otherwise, Find checks if an element equivalent to Item is present in Container. If a match is found, a cursor designating the matching element is returned; otherwise, No_Element is returned.
function Contains (Container : Set;
Item : Element_Type) return Boolean;
Equivalent to Find (Container, Item) /= No_Element.
Paragraphs 83 and 84 were moved above.
procedure Iterate
(Container : in Set;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
Iterate calls Process.all with a cursor that designates each element in Container, starting with the first element and moving the cursor according to the successor relation. Tampering with the cursors of Container is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
Both Containers.Hashed_Set and Containers.Ordered_Set declare a nested generic package Generic_Keys, which provides operations that allow set manipulation in terms of a key (typically, a portion of an element) instead of a complete element. The formal function Key of Generic_Keys extracts a key value from an element. It is expected to return the same value each time it is called with a particular element. The behavior of Generic_Keys is unspecified if Key behaves in some other manner.
A key is expected to unambiguously determine a single equivalence class for elements. The behavior of Generic_Keys is unspecified if the formal parameters of this package behave in some other manner.
function Key (Position : Cursor) return Key_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Key (Element (Position)).
function Key (Container : Set;
Position : Cursor) return Key_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Equivalent to Key (Element (Container, Position)).
The subprograms in package Generic_Keys named Contains, Find, Element, Delete, and Exclude, are equivalent to the corresponding subprograms in the parent package, with the difference that the Key parameter is used to locate an element in the set.
procedure Replace (Container : in out Set;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old;
Equivalent to Replace_Element (Container, Find (Container, Key), New_Item).
procedure Update_Element_Preserving_Key
(Container : in out Set;
Position : in Cursor;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Update_Element_Preserving_Key uses Key to save the key value K of the element designated by Position. Update_Element_Preserving_Key then calls Process.all with that element as the argument. Tampering with the cursors of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated. After Process.all returns, Update_Element_Preserving_Key checks if K determines the same equivalence class as that for the new element; if not, the element is removed from the set and Program_Error is propagated.
If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all shall be unconstrained.
type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
The type Reference_Type needs finalization.
This paragraph was deleted.
function Reference_Preserving_Key (Container : aliased in out Set;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
This function (combined with the Implicit_Dereference aspect) provides a convenient way to gain read and write access to an individual element of a set given a cursor.
Reference_Preserving_Key uses Key to save the key value K; then returns an object whose discriminant is an access value that designates the element designated by Position. Tampering with the cursors of Container is prohibited while the object returned by Reference_Preserving_Key exists and has not been finalized. When the object returned by Reference_Preserving_Key is finalized, a check is made if K determines the same equivalence class as that for the new element; if not, the element is removed from the set and Program_Error is propagated.
function Constant_Reference (Container : aliased in Set;
Key : in Key_Type)
return Constant_Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container);
This function (combined with the Implicit_Dereference aspect) provides a convenient way to gain read access to an individual element of a set given a key value.
Equivalent to Constant_Reference (Container, Find (Container, Key)).
function Reference_Preserving_Key (Container : aliased in out Set;
Key : in Key_Type)
return Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container);
This function (combined with the Implicit_Dereference aspect) provides a convenient way to gain read and write access to an individual element of a set given a key value.
Equivalent to Reference_Preserving_Key (Container, Find (Container, Key)).
The nested package Stable provides a type Stable.Set that represents a stable set, which is one that cannot grow and shrink. Such a set can be created by calling the Copy function, or by establishing a stabilized view of an ordinary set.
The subprograms of the set package that have a parameter or result of type Set are included in the nested package Stable with the same specification, except that the following are omitted:
Tampering_With_Cursors_Prohibited, Assign, Move, Insert, Include, Clear, Delete, Exclude, Replace, Replace_Element, procedures Union, Intersection, Difference, and Symmetric_Difference, (for Ordered_sets) Delete_First and Delete_Last, and (for Hashed_sets) Reserve_Capacity
The operations of this package are equivalent to those for ordinary sets, except that the calls to Tampering_With_Cursors_Prohibited that occur in preconditions are replaced by False, and any that occur in postconditions are replaced by True.
If a stable set is declared with the Base discriminant designating a pre-existing ordinary set, the stable set represents a stabilized view of the underlying ordinary set, and any operation on the stable set is reflected on the underlying ordinary set. While a stabilized view exists, any operation that tampers with cursors performed on the underlying set is prohibited. The finalization of a stable set that provides such a view removes this restriction on the underlying ordinary set [(though some other restriction can exist due to other concurrent iterations or stabilized views)].
If a stable set is declared without specifying Base, the object is necessarily initialized. The initializing expression of the stable set, [typically a call on Copy], determines the Length of the set. The Length of a stable set never changes after initialization.
Bounded (Run-Time) Errors
96.19/3It is a bounded error for the actual function associated with a generic formal subprogram, when called as part of an operation of a set package, to tamper with elements of any set parameter of the operation. Either Program_Error is raised, or the operation works as defined on the value of the set either prior to, or subsequent to, some or all of the modifications to the set.
It is a bounded error to call any subprogram declared in the visible part of a set package when the associated container has been finalized. If the operation takes Container as an in out parameter, then it raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for an empty container, or it raises Constraint_Error or Program_Error.
Erroneous Execution
97/2A Cursor value is invalid if any of the following have occurred since it was created:
- The set that contains the element it designates has been finalized;
- The set that contains the element it designates has been used as the Target of a call to Assign, or as the target of an
assignment_statement; 99/2 - The set that contains the element it designates has been used as the Source or Target of a call to Move; or
- The element it designates has been removed from the set that previously contained the element.
The result of "=" or Has_Element is unspecified if these functions are called with an invalid cursor parameter. Execution is erroneous if any other subprogram declared in Containers.Hashed_Sets or Containers.Ordered_Sets is called with an invalid cursor parameter.
Execution is erroneous if the set associated with the result of a call to Reference or Constant_Reference is finalized before the result object returned by the call to Reference or Constant_Reference is finalized.
Implementation Requirements
102/5No storage associated with a set object shall be lost upon assignment or scope exit.
The execution of an assignment_statement for a set shall have the effect of copying the elements from the source set object to the target set object and changing the length of the target object to that of the source object.
Implementation Advice
104/2Move should not copy elements, and should minimize copying of internal data structures.
If an exception is propagated from a set operation, no storage should be lost, nor any elements removed from a set unless specified by the operation.
Wording Changes from Ada 95
Extensions to Ada 2005
Wording Changes from Ada 2005
Inconsistencies With Ada 2012
Extensions to Ada 2012
Wording Changes from Ada 2012
A.18.8 The Generic Package Containers.Hashed_Sets
Static Semantics
1/2The generic library package Containers.Hashed_Sets has the following declaration:
with Ada.Iterator_Interfaces;
generic
type Element_Type is private;
with function Hash (Element : Element_Type) return Hash_Type;
with function Equivalent_Elements (Left, Right : Element_Type)
return Boolean;
with function "=" (Left, Right : Element_Type) return Boolean is <>;
package Ada.Containers.Hashed_Sets
with Preelaborate, Remote_Types,
Nonblocking, Global => in out synchronized is
type Set is tagged private
with Constant_Indexing => Constant_Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Iterator_View => Stable.Set,
Aggregate => (Empty => Empty,
Add_Unnamed => Include),
Stable_Properties => (Length,
Tampering_With_Cursors_Prohibited),
Default_Initial_Condition =>
Length (Set) = 0 and then
(not Tampering_With_Cursors_Prohibited (Set)),
Preelaborable_Initialization ;
type Cursor is private
with Preelaborable_Initialization ;
5/2Empty_Set : constant Set;
6/2No_Element : constant Cursor;
6.1/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
6.2/5function Has_Element (Container : Set; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
6.3/3package Set_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
7/2function "=" (Left, Right : Set) return Boolean;
8/2function Equivalent_Sets (Left, Right : Set) return Boolean;
8.1/5function Tampering_With_Cursors_Prohibited
(Container : Set) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
8.2/5function Empty (Capacity : Count_Type := implementation-defined)
return Set
with Post =>
Capacity (Empty'Result) >= Capacity and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
9/5function To_Set (New_Item : Element_Type) return Set
with Post => Length (To_Set'Result) = 1 and then
not Tampering_with_Cursors_Prohibited (To_Set'Result);
10/5function Capacity (Container : Set) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
11/5procedure Reserve_Capacity (Container : in out Set;
Capacity : in Count_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Container.Capacity >= Capacity;
12/5function Length (Container : Set) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
13/5function Is_Empty (Container : Set) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Length (Container) = 0);
14/5procedure Clear (Container : in out Set)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Capacity (Container) = Capacity (Container)'Old and then
Length (Container) = 0;
15/5function Element (Position : Cursor) return Element_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Element_Type;
15.1/5function Element (Container : Set;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
16/5procedure Replace_Element (Container : in out Set;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
17/5procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
17.1/5procedure Query_Element
(Container : in Set;
Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
17.2/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
17.3/5function Constant_Reference (Container : aliased in Set;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
17.4/5procedure Assign (Target : in out Set; Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target) and then
Capacity (Target) >= Length (Source);
17.5/5function Copy (Source : Set; Capacity : Count_Type := 0)
return Set
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Cursors_Prohibited (Copy'Result) and then
Copy'Result.Capacity = (if Capacity = 0 then
Length (Source) else Capacity);
18/5procedure Move (Target : in out Set;
Source : in out Set)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Length (Target) = Length (Source'Old) and then
Length (Source) = 0);
19/5procedure Insert (Container : in out Set;
New_Item : in Element_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length)) and then
Capacity (Container) >= Length (Container);
20/5procedure Insert (Container : in out Set;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => Length (Container) = Length (Container)'Old + 1 and then
Capacity (Container) >= Length (Container);
21/5procedure Include (Container : in out Set;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length | Original_Length + 1) and then
Capacity (Container) >= Length (Container);
22/5procedure Replace (Container : in out Set;
New_Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old;
23/5procedure Exclude (Container : in out Set;
Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container) in
Original_Length - 1 | Original_Length);
24/5procedure Delete (Container : in out Set;
Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old - 1;
25/5procedure Delete (Container : in out Set;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Length (Container) = Length (Container)'Old - 1 and then
Position = No_Element;
26/5procedure Union (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
27/5function Union (Left, Right : Set) return Set
with Post => Length (Union'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (Union'Result);
28/2function "or" (Left, Right : Set) return Set renames Union;
29/5procedure Intersection (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
30/5function Intersection (Left, Right : Set) return Set
with Post =>
Length (Intersection'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (Intersection'Result);
31/2function "and" (Left, Right : Set) return Set renames Intersection;
32/5procedure Difference (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
33/5function Difference (Left, Right : Set) return Set
with Post =>
Length (Difference'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (Difference'Result);
34/2function "-" (Left, Right : Set) return Set renames Difference;
35/5procedure Symmetric_Difference (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
36/5function Symmetric_Difference (Left, Right : Set) return Set
with Post =>
Length (Symmetric_Difference'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (
Symmetric_Difference'Result);
37/2function "xor" (Left, Right : Set) return Set
renames Symmetric_Difference;
38/2function Overlap (Left, Right : Set) return Boolean;
39/2function Is_Subset (Subset : Set;
Of_Set : Set) return Boolean;
40/5function First (Container : Set) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, First'Result)
else First'Result = No_Element);
41/5function Next (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then Next'Result = No_Element);
41.1/5function Next (Container : Set;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Next'Result = No_Element
elsif Next'Result = No_Element then
Position = Last (Container)
else Has_Element (Container, Next'Result));
42/5procedure Next (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
42.1/5procedure Next (Container : in Set;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
43/5function Find (Container : Set;
Item : Element_Type)
return Cursor
with Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
44/2function Contains (Container : Set;
Item : Element_Type) return Boolean;
45/3This paragraph was deleted.
46/5function Equivalent_Elements (Left, Right : Cursor)
return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
47/5function Equivalent_Elements (Left : Cursor;
Right : Element_Type)
return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
48/5function Equivalent_Elements (Left : Element_Type;
Right : Cursor)
return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
49/5procedure Iterate
(Container : in Set;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
49.1/5function Iterate (Container : in Set)
return Set_Iterator_Interfaces.Parallel_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
50/5generic
type Key_Type (<>) is private;
with function Key (Element : Element_Type) return Key_Type;
with function Hash (Key : Key_Type) return Hash_Type;
with function Equivalent_Keys (Left, Right : Key_Type)
return Boolean;
package Generic_Keys
with Nonblocking, Global => null is
51/5function Key (Position : Cursor) return Key_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
51.1/5function Key (Container : Set;
Position : Cursor) return Key_Type
with Pre => (Position = No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
52/2function Element (Container : Set;
Key : Key_Type)
return Element_Type;
53/5procedure Replace (Container : in out Set;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old;
54/5procedure Exclude (Container : in out Set;
Key : in Key_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length - 1 | Original_Length);
55/5procedure Delete (Container : in out Set;
Key : in Key_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old - 1;
56/5function Find (Container : Set;
Key : Key_Type)
return Cursor
with Post => (if Find'Result = No_Element
then Has_Element (Container, Find'Result));
57/2function Contains (Container : Set;
Key : Key_Type)
return Boolean;
58/5procedure Update_Element_Preserving_Key
(Container : in out Set;
Position : in Cursor;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Container, Position) or else
raise Program_Error);
58.1/5type Reference_Type
(Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
58.2/5function Reference_Preserving_Key (Container : aliased in out Set;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
58.3/5function Constant_Reference (Container : aliased in Set;
Key : in Key_Type)
return Constant_Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container);
58.4/5function Reference_Preserving_Key (Container : aliased in out Set;
Key : in Key_Type)
return Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container);
59/2end Generic_Keys;
59.1/5package Stable is
59.2/5type Set (Base : not null access Hashed_Sets.Set) is
tagged limited private
with Constant_Indexing => Constant_Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Stable_Properties => (Length),
Global => null,
Default_Initial_Condition => Length (Set) = 0,
Preelaborable_Initialization;
59.3/5type Cursor is private
with Preelaborable_Initialization;
59.4/5Empty_Set : constant Set;
59.5/5No_Element : constant Cursor;
59.6/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
59.7/5package Set_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
59.8/5procedure Assign (Target : in out Hashed_Sets.Set;
Source : in Set)
with Post => Length (Source) = Length (Target);
59.9/5function Copy (Source : Hashed_Sets.Set) return Set
with Post => Length (Copy'Result) = Length (Source);
59.10/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null, Use_Formal => null,
Default_Initial_Condition => (raise Program_Error);
59.11/5-- Additional subprograms as described in the text
-- are declared here.
59.12/5private
59.13/5... -- not specified by the language
59.14/5end Stable;
60/2private
61/2... -- not specified by the language
62/2end Ada.Containers.Hashed_Sets;
An object of type Set contains an expandable hash table, which is used to provide direct access to elements. The capacity of an object of type Set is the maximum number of elements that can be inserted into the hash table prior to it being automatically expanded.
Two elements E1 and E2 are defined to be equivalent if Equivalent_Elements (E1, E2) returns True.
The actual function for the generic formal function Hash is expected to return the same value each time it is called with a particular element value. For any two equivalent elements, the actual for Hash is expected to return the same value. If the actual for Hash behaves in some other manner, the behavior of this package is unspecified. Which subprograms of this package call Hash, and how many times they call it, is unspecified.
The actual function for the generic formal function Equivalent_Elements is expected to return the same value each time it is called with a particular pair of Element values. It should define an equivalence relationship, that is, be reflexive, symmetric, and transitive. If the actual for Equivalent_Elements behaves in some other manner, the behavior of this package is unspecified. Which subprograms of this package call Equivalent_Elements, and how many times they call it, is unspecified.
If the actual function for the generic formal function "=" returns True for any pair of nonequivalent elements, then the behavior of the container function "=" is unspecified.
If the value of an element stored in a set is changed other than by an operation in this package such that at least one of Hash or Equivalent_Elements give different results, the behavior of this package is unspecified.
Which elements are the first element and the last element of a set, and which element is the successor of a given element, are unspecified, other than the general semantics described in A.18.7.
function Empty (Capacity : Count_Type := implementation-defined)
return Set
with Post =>
Capacity (Empty'Result) >= Capacity and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
Returns an empty set.
function Capacity (Container : Set) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
Returns the capacity of Container.
procedure Reserve_Capacity (Container : in out Set;
Capacity : in Count_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Container.Capacity >= Capacity;
Reserve_Capacity allocates a new hash table such that the length of the resulting set can become at least the value Capacity without requiring an additional call to Reserve_Capacity, and is large enough to hold the current length of Container. Reserve_Capacity then rehashes the elements in Container onto the new hash table. It replaces the old hash table with the new hash table, and then deallocates the old hash table. Any exception raised during allocation is propagated and Container is not modified.
This paragraph was deleted.
procedure Clear (Container : in out Set)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Capacity (Container) = Capacity (Container)'Old and then
Length (Container) = 0;
In addition to the semantics described in A.18.7, Clear does not affect the capacity of Container.
procedure Assign (Target : in out Set; Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target) and then
Capacity (Target) >= Length (Source);
In addition to the semantics described in A.18.7, if the length of Source is greater than the capacity of Target, Reserve_Capacity (Target, Length (Source)) is called before assigning any elements.
function Copy (Source : Set; Capacity : Count_Type := 0)
return Set
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Cursors_Prohibited (Copy'Result) and then
Copy'Result.Capacity = (if Capacity = 0 then
Length (Source) else Capacity);
Returns a set whose elements are initialized from the elements of Source.
procedure Insert (Container : in out Set;
New_Item : in Element_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length)) and then
Capacity (Container) >= Length (Container);
In addition to the semantics described in A.18.7, if Length (Container) equals Capacity (Container), then Insert first calls Reserve_Capacity to increase the capacity of Container to some larger value.
function First (Container : Set) return Cursor;
If Length (Container) = 0, then First returns No_Element. Otherwise, First returns a cursor that designates the first hashed element in Container.
function Equivalent_Elements (Left, Right : Cursor)
return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
Equivalent to Equivalent_Elements (Element (Left), Element (Right)).
function Equivalent_Elements (Left : Cursor;
Right : Element_Type) return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Equivalent_Elements (Element (Left), Right).
function Equivalent_Elements (Left : Element_Type;
Right : Cursor) return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Equivalent_Elements (Left, Element (Right)).
function Iterate (Container : in Set)
return Set_Iterator_Interfaces.Parallel_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each element in Container, starting with the first element and moving the cursor according to the successor relation when used as a forward iterator, and processing all nodes concurrently when used as a parallel iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
For any element E, the actual function for the generic formal function Generic_Keys.Hash is expected to be such that Hash (E) = Generic_Keys.Hash (Key (E)). If the actuals for Key or Generic_Keys.Hash behave in some other manner, the behavior of Generic_Keys is unspecified. Which subprograms of Generic_Keys call Generic_Keys.Hash, and how many times they call it, is unspecified.
For any two elements E1 and E2, the boolean values Equivalent_Elements (E1, E2) and Equivalent_Keys (Key (E1), Key (E2)) are expected to be equal. If the actuals for Key or Equivalent_Keys behave in some other manner, the behavior of Generic_Keys is unspecified. Which subprograms of Generic_Keys call Equivalent_Keys, and how many times they call it, is unspecified.
Implementation Advice
88/2If N is the length of a set, the average time complexity of the subprograms Insert, Include, Replace, Delete, Exclude, and Find that take an element parameter should be O(log N). The average time complexity of the subprograms that take a cursor parameter should be O(1). The average time complexity of Reserve_Capacity should be O(N).
Extensions to Ada 95
Incompatibilities With Ada 2005
use_clause, and an entity E with the same defining_identifier as a new entity in Containers.Hashed_Sets is defined in a package that is also referenced in a use_clause, the entity E may no longer be use-visible, resulting in errors. This should be rare and is easily fixed if it does occur. Extensions to Ada 2005
Wording Changes from Ada 2005
Incompatibilities With Ada 2012
Extensions to Ada 2012
aggregate syntax can be used to create Sets.Wording Changes from Ada 2012
A.18.9 The Generic Package Containers.Ordered_Sets
Static Semantics
1/2The generic library package Containers.Ordered_Sets has the following declaration:
with Ada.Iterator_Interfaces;
generic
type Element_Type is private;
with function "<" (Left, Right : Element_Type) return Boolean is <>;
with function "=" (Left, Right : Element_Type) return Boolean is <>;
package Ada.Containers.Ordered_Sets
with Preelaborate, Remote_Types,
Nonblocking, Global => in out synchronized is
function Equivalent_Elements (Left, Right : Element_Type) return Boolean;
4/5type Set is tagged private
with Constant_Indexing => Constant_Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Iterator_View => Stable.Set,
Aggregate => (Empty => Empty,
Add_Unnamed => Include),
Stable_Properties => (Length,
Tampering_With_Cursors_Prohibited),
Default_Initial_Condition =>
Length (Set) = 0 and then
(not Tampering_With_Cursors_Prohibited (Set)),
Preelaborable_Initialization ;
5/5type Cursor is private
with Preelaborable_Initialization ;
6/2Empty_Set : constant Set;
7/2No_Element : constant Cursor;
7.1/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
7.2/5function Has_Element (Container : Set; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
7.3/3package Set_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
8/2function "=" (Left, Right : Set) return Boolean;
9/2function Equivalent_Sets (Left, Right : Set) return Boolean;
9.1/5function Tampering_With_Cursors_Prohibited
(Container : Set) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
9.2/5function Empty return Set
is (Empty_Set)
with Post =>
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
10/5function To_Set (New_Item : Element_Type) return Set
with Post => Length (To_Set'Result) = 1 and then
not Tampering_with_Cursors_Prohibited (To_Set'Result);
11/5function Length (Container : Set) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
12/5function Is_Empty (Container : Set) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Length (Container) = 0);
13/5procedure Clear (Container : in out Set)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = 0;
14/5function Element (Position : Cursor) return Element_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => Element_Type;
14.1/5function Element (Container : Set;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
15/5procedure Replace_Element (Container : in out Set;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
16/5procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => Position /= No_Element
or else raise Constraint_Error,
Global => in all;
16.1/5procedure Query_Element
(Container : in Set;
Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
16.2/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
16.3/5function Constant_Reference (Container : aliased in Set;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
16.4/5procedure Assign (Target : in out Set; Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Source) = Length (Target);
16.5/5function Copy (Source : Set) return Set
with Post => Length (Copy'Result) = Length (Source) and then
not Tampering_With_Cursors_Prohibited (Copy'Result);
17/5procedure Move (Target : in out Set;
Source : in out Set)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Length (Target) = Length (Source'Old) and then
Length (Source) = 0);
18/5procedure Insert (Container : in out Set;
New_Item : in Element_Type;
Position : out Cursor;
Inserted : out Boolean)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Has_Element (Container, Position) and then
(if Inserted then
Length (Container) = Original_Length + 1
else
Length (Container) = Original_Length));
19/5procedure Insert (Container : in out Set;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => Length (Container) = Length (Container)'Old + 1;
20/5procedure Include (Container : in out Set;
New_Item : in Element_Type)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Length (Container) <= Count_Type'Last - 1
or else raise Constraint_Error),
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length | Original_Length + 1);
21/5procedure Replace (Container : in out Set;
New_Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old;
22/5procedure Exclude (Container : in out Set;
Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container)
in Original_Length - 1 | Original_Length);
23/5procedure Delete (Container : in out Set;
Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old - 1;
24/5procedure Delete (Container : in out Set;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Length (Container) = Length (Container)'Old - 1 and then
Position = No_Element;
25/5procedure Delete_First (Container : in out Set)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
(if Original_Length = 0 then Length (Container) = 0
else Length (Container) = Original_Length - 1));
26/5procedure Delete_Last (Container : in out Set)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
(if Original_Length = 0 then Length (Container) = 0
else Length (Container) = Original_Length - 1));
27/5procedure Union (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
28/5function Union (Left, Right : Set) return Set
with Post => Length (Union'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (Union'Result);
29/2function "or" (Left, Right : Set) return Set renames Union;
30/5procedure Intersection (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
31/5function Intersection (Left, Right : Set) return Set
with Post =>
Length (Intersection'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (Intersection'Result);
32/2function "and" (Left, Right : Set) return Set renames Intersection;
33/5procedure Difference (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
34/5function Difference (Left, Right : Set) return Set
with Post =>
Length (Difference'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (Difference'Result);
35/2function "-" (Left, Right : Set) return Set renames Difference;
36/5procedure Symmetric_Difference (Target : in out Set;
Source : in Set)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Length (Target) <= Length (Target)'Old + Length (Source);
37/5function Symmetric_Difference (Left, Right : Set) return Set
with Post =>
Length (Symmetric_Difference'Result) <=
Length (Left) + Length (Right) and then
not Tampering_With_Cursors_Prohibited (
Symmetric_Difference'Result);
38/2function "xor" (Left, Right : Set) return Set renames
Symmetric_Difference;
39/2function Overlap (Left, Right : Set) return Boolean;
40/2function Is_Subset (Subset : Set;
Of_Set : Set) return Boolean;
41/5function First (Container : Set) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container)
then Has_Element (Container, First'Result)
else First'Result = No_Element);
42/5function First_Element (Container : Set)
return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
43/5function Last (Container : Set) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container) then
Has_Element (Container, Last'Result)
else Last'Result = No_Element);
44/5function Last_Element (Container : Set)
return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
45/5function Next (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then Next'Result = No_Element);
45.1/5function Next (Container : Set;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then Next'Result = No_Element
elsif Next'Result = No_Element then
Position = Last (Container)
else Has_Element (Container, Next'Result));
46/5procedure Next (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
46.1/5procedure Next (Container : in Set;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
47/5function Previous (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then
Previous'Result = No_Element);
47.1/5function Previous (Container : Set;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then
Previous'Result = No_Element
elsif Previous'Result = No_Element then
Position = First (Container)
else Has_Element (Container, Previous'Result));
48/5procedure Previous (Position : in out Cursor)
with Nonblocking, Global => in all,
Use_Formal => null;
48.1/5procedure Previous (Container : in Set;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
49/5function Find (Container : Set;
Item : Element_Type) return Cursor
with Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
50/2function Floor (Container : Set;
Item : Element_Type) return Cursor
with Post => (if Floor'Result /= No_Element
then Has_Element (Container, Floor'Result));
51/2function Ceiling (Container : Set;
Item : Element_Type) return Cursor
with Post => (if Ceiling'Result /= No_Element
then Has_Element (Container, Ceiling'Result));
52/2function Contains (Container : Set;
Item : Element_Type) return Boolean;
53/3This paragraph was deleted.
54/5function "<" (Left, Right : Cursor) return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
55/5function ">" (Left, Right : Cursor) return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
56/5function "<" (Left : Cursor; Right : Element_Type) return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
57/5function ">" (Left : Cursor; Right : Element_Type) return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
58/5function "<" (Left : Element_Type; Right : Cursor) return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
59/5function ">" (Left : Element_Type; Right : Cursor) return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
60/5procedure Iterate
(Container : in Set;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
61/5procedure Reverse_Iterate
(Container : in Set;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
61.1/5function Iterate (Container : in Set)
return Set_Iterator_Interfaces.Parallel_Reversible_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
61.2/5function Iterate (Container : in Set; Start : in Cursor)
return Set_Iterator_Interfaces.Reversible_Iterator'Class
with Pre => (Start /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Start)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
62/5generic
type Key_Type (<>) is private;
with function Key (Element : Element_Type) return Key_Type;
with function "<" (Left, Right : Key_Type)
return Boolean is <>;
package Generic_Keys
with Nonblocking, Global => null is
63/2function Equivalent_Keys (Left, Right : Key_Type)
return Boolean;
64/5function Key (Position : Cursor) return Key_Type
with Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
64.1/5function Key (Container : Set;
Position : Cursor) return Key_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
65/2function Element (Container : Set;
Key : Key_Type)
return Element_Type;
66/5procedure Replace (Container : in out Set;
Key : in Key_Type;
New_Item : in Element_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old;
67/5procedure Exclude (Container : in out Set;
Key : in Key_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
Length (Container) in
Original_Length - 1 | Original_Length);
68/5procedure Delete (Container : in out Set;
Key : in Key_Type)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Length (Container) = Length (Container)'Old - 1;
69/5function Find (Container : Set;
Key : Key_Type) return Cursor
with Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
70/5function Floor (Container : Set;
Key : Key_Type) return Cursor
with Post => (if Floor'Result /= No_Element
then Has_Element (Container, Floor'Result));
71/5function Ceiling (Container : Set;
Key : Key_Type) return Cursor
with Post => (if Ceiling'Result /= No_Element
then Has_Element (Container, Ceiling'Result));
72/2function Contains (Container : Set;
Key : Key_Type) return Boolean;
73/5procedure Update_Element_Preserving_Key
(Container : in out Set;
Position : in Cursor;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
73.1/5type Reference_Type
(Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
73.2/5function Reference_Preserving_Key (Container : aliased in out Set;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);;
73.3/5function Constant_Reference (Container : aliased in Set;
Key : in Key_Type)
return Constant_Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container);;
73.4/5function Reference_Preserving_Key (Container : aliased in out Set;
Key : in Key_Type)
return Reference_Type
with Pre => Find (Container, Key) /= No_Element
or else raise Constraint_Error,
Post => Tampering_With_Cursors_Prohibited (Container);;
74/2end Generic_Keys;
74.1/5package Stable is
74.2/5type Set (Base : not null access Ordered_Sets.Set) is
tagged limited private
with Constant_Indexing => Constant_Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Stable_Properties => (Length),
Global => null,
Default_Initial_Condition => Length (Set) = 0,
Preelaborable_Initialization;
74.3/5type Cursor is private
with Preelaborable_Initialization;
74.4/5Empty_Set : constant Set;
74.5/5No_Element : constant Cursor;
74.6/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
74.7/5package Set_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
74.8/5procedure Assign (Target : in out Ordered_Sets.Set;
Source : in Set)
with Post => Length (Source) = Length (Target);
74.9/5function Copy (Source : Ordered_Sets.Set) return Set
with Post => Length (Copy'Result) = Length (Source);
74.10/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null, Use_Formal => null,
Default_Initial_Condition => (raise Program_Error);
74.11/5-- Additional subprograms as described in the text
-- are declared here.
74.12/5private
74.13/5... -- not specified by the language
74.14/5end Stable;
75/2private
76/2... -- not specified by the language
77/2end Ada.Containers.Ordered_Sets;
Two elements E1 and E2 are equivalent if both E1 < E2 and E2 < E1 return False, using the generic formal "<" operator for elements. Function Equivalent_Elements returns True if Left and Right are equivalent, and False otherwise.
The actual function for the generic formal function "<" on Element_Type values is expected to return the same value each time it is called with a particular pair of key values. It should define a strict weak ordering relationship (see A.18). If the actual for "<" behaves in some other manner, the behavior of this package is unspecified. Which subprograms of this package call "<" and how many times they call it, is unspecified.
If the actual function for the generic formal function "=" returns True for any pair of nonequivalent elements, then the behavior of the container function "=" is unspecified.
If the value of an element stored in a set is changed other than by an operation in this package such that at least one of "<" or "=" give different results, the behavior of this package is unspecified.
The first element of a nonempty set is the one which is less than all the other elements in the set. The last element of a nonempty set is the one which is greater than all the other elements in the set. The successor of an element is the smallest element that is larger than the given element. The predecessor of an element is the largest element that is smaller than the given element. All comparisons are done using the generic formal "<" operator for elements.
function Copy (Source : Set) return Set
with Post => Length (Copy'Result) = Length (Source) and then
not Tampering_With_Cursors_Prohibited (Copy'Result);
Returns a set whose elements are initialized from the corresponding elements of Source.
procedure Delete_First (Container : in out Set)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
(if Original_Length = 0 then Length (Container) = 0
else Length (Container) = Original_Length - 1));
If Container is empty, Delete_First has no effect. Otherwise, the element designated by First (Container) is removed from Container. Delete_First tampers with the cursors of Container.
procedure Delete_Last (Container : in out Set)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => (declare
Original_Length : constant Count_Type :=
Length (Container)'Old;
begin
(if Original_Length = 0 then Length (Container) = 0
else Length (Container) = Original_Length - 1));
If Container is empty, Delete_Last has no effect. Otherwise, the element designated by Last (Container) is removed from Container. Delete_Last tampers with the cursors of Container.
function First_Element (Container : Set) return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
Equivalent to Element (First (Container)).
function Last (Container : Set) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => (if not Is_Empty (Container) then
Has_Element (Container, Last'Result)
else Last'Result = No_Element);
Returns a cursor that designates the last element in Container. If Container is empty, returns No_Element.
function Last_Element (Container : Set) return Element_Type
with Pre => (not Is_Empty (Container)
or else raise Constraint_Error);
Equivalent to Element (Last (Container)).
function Previous (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element then
Previous'Result = No_Element);
If Position equals No_Element, then Previous returns No_Element. Otherwise, Previous returns a cursor designating the predecessor element of the one designated by Position. If Position designates the first element, then Previous returns No_Element.
function Previous (Container : Set;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element then
Previous'Result = No_Element
elsif Previous'Result = No_Element then
Position = First (Container)
else Has_Element (Container, Previous'Result));
Returns a cursor designating the predecessor of the node designated by Position in Container, if any.
procedure Previous (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
Equivalent to Position := Previous (Position).
procedure Previous (Container : in Set;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Position = No_Element or else
Has_Element (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
Equivalent to Position := Previous (Container, Position).
function Floor (Container : Set;
Item : Element_Type) return Cursor
with Post => (if Floor'Result /= No_Element
then Has_Element (Container, Floor'Result));
Floor searches for the last element which is not greater than Item. If such an element is found, a cursor that designates it is returned. Otherwise, No_Element is returned.
function Ceiling (Container : Set;
Item : Element_Type) return Cursor
with Post => (if Ceiling'Result /= No_Element
then Has_Element (Container, Ceiling'Result));
Ceiling searches for the first element which is not less than Item. If such an element is found, a cursor that designates it is returned. Otherwise, No_Element is returned.
function "<" (Left, Right : Cursor) return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
Equivalent to Element (Left) < Element (Right).
function ">" (Left, Right : Cursor) return Boolean
with Pre => (Left /= No_Element and then Right /= No_Element)
or else raise Constraint_Error,
Global => in all;
Equivalent to Element (Right) < Element (Left).
function "<" (Left : Cursor; Right : Element_Type) return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Element (Left) < Right.
function ">" (Left : Cursor; Right : Element_Type) return Boolean
with Pre => Left /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Right < Element (Left).
function "<" (Left : Element_Type; Right : Cursor) return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Left < Element (Right).
function ">" (Left : Element_Type; Right : Cursor) return Boolean
with Pre => Right /= No_Element or else raise Constraint_Error,
Global => in all;
Equivalent to Element (Right) < Left.
procedure Reverse_Iterate
(Container : in Set;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
Iterates over the elements in Container as per procedure Iterate, with the difference that the elements are traversed in predecessor order, starting with the last element.
function Iterate (Container : in Set)
return Set_Iterator_Interfaces.Parallel_Reversible_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each element in Container, starting with the first element and moving the cursor according to the successor relation when used as a forward iterator, and starting with the last element and moving the cursor according to the predecessor relation when used as a reverse iterator, and processing all nodes concurrently when used as a parallel iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
function Iterate (Container : in Set; Start : in Cursor)
return Set_Iterator_Interfaces.Reversible_Iterator'Class
with Pre => (Start /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Start)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns a reversible iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each element in Container, starting with the element designated by Start and moving the cursor according to the successor relation when used as a forward iterator, or moving the cursor according to the predecessor relation when used as a reverse iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
exit when Cur = Stop;
For any two elements E1 and E2, the boolean values (E1 < E2) and (Key(E1) < Key(E2)) are expected to be equal. If the actuals for Key or Generic_Keys."<" behave in some other manner, the behavior of this package is unspecified. Which subprograms of this package call Key and Generic_Keys."<", and how many times the functions are called, is unspecified.
In addition to the semantics described in A.18.7, the subprograms in package Generic_Keys named Floor and Ceiling, are equivalent to the corresponding subprograms in the parent package, with the difference that the Key subprogram parameter is compared to elements in the container using the Key and "<" generic formal functions. The function named Equivalent_Keys in package Generic_Keys returns True if both Left < Right and Right < Left return False using the generic formal "<" operator, and returns True otherwise.
Implementation Advice
116/2If N is the length of a set, then the worst-case time complexity of the Insert, Include, Replace, Delete, Exclude, and Find operations that take an element parameter should be O((log N)**2) or better. The worst-case time complexity of the subprograms that take a cursor parameter should be O(1).
Extensions to Ada 95
Incompatibilities With Ada 2005
use_clause, and an entity E with the same defining_identifier as a new entity in Containers.Ordered_Sets is defined in a package that is also referenced in a use_clause, the entity E may no longer be use-visible, resulting in errors. This should be rare and is easily fixed if it does occur. Extensions to Ada 2005
Wording Changes from Ada 2005
Incompatibilities With Ada 2012
Extensions to Ada 2012
aggregate syntax can be used to create Sets.Wording Changes from Ada 2012
A.18.10 The Generic Package Containers.Multiway_Trees
1/3The language-defined generic package Containers.Multiway_Trees provides private types Tree and Cursor, and a set of operations for each type. A multiway tree container is well-suited to represent nested structures.
A multiway tree container object manages a tree of nodes, consisting of a root node and a set of internal nodes; each internal node contains an element and pointers to the parent, first child, last child, next (successor) sibling, and previous (predecessor) sibling internal nodes. A cursor designates a particular node within a tree (and by extension the element contained in that node, if any). A cursor keeps designating the same node (and element) as long as the node is part of the container, even if the node is moved within the container.
A subtree is a particular node (which roots the subtree) and all of its child nodes (including all of the children of the child nodes, recursively). The root node is always present and has neither an associated element value nor any parent node; it has pointers to its first child and its last child, if any. The root node provides a place to add nodes to an otherwise empty tree and represents the base of the tree.
A node that has no children is called a leaf node. The ancestors of a node are the node itself, its parent node, the parent of the parent node, and so on until a node with no parent is reached. Similarly, the descendants of a node are the node itself, its child nodes, the children of each child node, and so on.
The nodes of a subtree can be visited in several different orders. For a depth-first order, after visiting a node, the nodes of its child list are each visited in depth-first order, with each child node visited in natural order (first child to last child).
Static Semantics
6/3The generic library package Containers.Multiway_Trees has the following declaration:
with Ada.Iterator_Interfaces;
generic
type Element_Type is private;
with function "=" (Left, Right : Element_Type) return Boolean is <>;
package Ada.Containers.Multiway_Trees
with Preelaborate, Remote_Types,
Nonblocking, Global => in out synchronized is
type Tree is tagged private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Iterator_View => Stable.Tree,
Stable_Properties => (Node_Count,
Tampering_With_Cursors_Prohibited,
Tampering_With_Elements_Prohibited),
Default_Initial_Condition =>
Node_Count (Tree) = 1 and then
(not Tampering_With_Cursors_Prohibited (Tree)) and then
(not Tampering_With_Elements_Prohibited (Tree)),
Preelaborable_Initialization ;
9/5type Cursor is private
with Preelaborable_Initialization ;
10/3Empty_Tree : constant Tree;
11/3No_Element : constant Cursor;
11.1/5function Equal_Element (Left, Right : Element_Type)
return Boolean renames "=";
12/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
12.1/5function Has_Element (Container : Tree; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
13/3package Tree_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
14/3function Equal_Subtree (Left_Position : Cursor;
Right_Position: Cursor) return Boolean;
15/3function "=" (Left, Right : Tree) return Boolean;
15.1/5function Tampering_With_Cursors_Prohibited
(Container : Tree) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
15.2/5function Tampering_With_Elements_Prohibited
(Container : Tree) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
15.3/5function Empty return Tree
is (Empty_Tree)
with Post =>
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Node_Count (Empty'Result) = 1;
16/5function Is_Empty (Container : Tree) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Node_Count (Container) = 1);
17/5function Node_Count (Container : Tree) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
18/5function Subtree_Node_Count (Position : Cursor) return Count_Type
with Nonblocking, Global => in all, Use_Formal => null;
18.1/5function Subtree_Node_Count (Container : Tree; Position : Cursor)
return Count_Type
with Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Nonblocking, Global => null, Use_Formal => null;
19/5function Depth (Position : Cursor) return Count_Type
with Nonblocking, Global => in all, Use_Formal => null;
19.1/5function Depth (Container : Tree; Position : Cursor)
return Count_Type
with Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Nonblocking, Global => null, Use_Formal => null;
20/5function Is_Root (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
20.1/5function Is_Root (Container : Tree; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
21/5function Is_Leaf (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
21.1/5function Is_Leaf (Container : Tree; Position : Cursor)
return Boolean
with Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Nonblocking, Global => null, Use_Formal => null;
21.2/5function Is_Ancestor_Of (Container : Tree;
Parent : Cursor;
Position : Cursor) return Boolean
with Pre => (Meaningful_For (Container, Position)
or else raise Program_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => null;
22/5function Root (Container : Tree) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => Root'Result /= No_Element and then
not Has_Element (Container, Root'Result);
22.1/5function Meaningful_For (Container : Tree; Position : Cursor)
return Boolean is
(Position = No_Element or else
Is_Root (Container, Position) or else
Has_Element (Container, Position))
with Nonblocking, Global => null, Use_Formal => null;
procedure Clear (Container : in out Tree)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Node_Count (Container) = 1;
24/5function Element (Position : Cursor) return Element_Type
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Position) or else raise Program_Error),
Nonblocking, Global => in all, Use_Formal => Element_Type;
24.1/5function Element (Container : Tree;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
25/5procedure Replace_Element (Container : in out Tree;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
26/5procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Position) or else raise Program_Error),
Global => in all;
26.1/5procedure Query_Element
(Container : in Tree;
Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
27/5procedure Update_Element
(Container : in out Tree;
Position : in Cursor;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
28/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
29/5type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
30/5function Constant_Reference (Container : aliased in Tree;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
31/5function Reference (Container : aliased in out Tree;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
32/5procedure Assign (Target : in out Tree; Source : in Tree)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Node_Count (Source) = Node_Count (Target);
33/5function Copy (Source : Tree) return Tree
with Post =>
Node_Count (Copy'Result) = Node_Count (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result);
34/5procedure Move (Target : in out Tree;
Source : in out Tree)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Node_Count (Target) = Node_Count (Source'Old) and then
Node_Count (Source) = 1);
35/5procedure Delete_Leaf (Container : in out Tree;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error) and then
(Is_Leaf (Container, Position)
or else raise Constraint_Error),
Post =>
Node_Count (Container)'Old = Node_Count (Container)+1 and then
Position = No_Element;
36/5procedure Delete_Subtree (Container : in out Tree;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Node_Count (Container)'Old = Node_Count (Container) +
Subtree_Node_Count (Container, Position)'Old and then
Position = No_Element;
37/5procedure Swap (Container : in out Tree;
I, J : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(I /= No_Element or else Constraint_Error) and then
(J /= No_Element or else Constraint_Error) and then
(Has_Element (Container, I)
or else raise Program_Error) and then
(Has_Element (Container, J)
or else raise Program_Error);
38/5function Find (Container : Tree;
Item : Element_Type)
return Cursor
with Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
39/5function Find_In_Subtree (Position : Cursor;
Item : Element_Type)
return Cursor
with Pre => Position /= No_Element or else raise Constraint_Error,
Post => (if Find_In_Subtree'Result = No_Element
then Has_Element (Find_In_Subtree'Result)),
Global => in all;
39.1/5function Find_In_Subtree (Container : Tree;
Position : Cursor;
Item : Element_Type)
return Cursor
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Position)
or else raise Program_Error),
Post => (if Find_In_Subtree'Result /= No_Element
then Has_Element (Container, Find_In_Subtree'Result));
40/5function Ancestor_Find (Position : Cursor;
Item : Element_Type)
return Cursor
with Pre => Position /= No_Element or else raise Constraint_Error,
Post => (if Ancestor_Find'Result = No_Element
then Has_Element (Ancestor_Find'Result)),
Global => in all;
40.1/5function Ancestor_Find (Container : Tree;
Position : Cursor;
Item : Element_Type)
return Cursor
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Position)
or else raise Program_Error),
Post => (if Ancestor_Find'Result = No_Element
then Has_Element (Container, Ancestor_Find'Result));
41/3function Contains (Container : Tree;
Item : Element_Type) return Boolean;
42/5procedure Iterate
(Container : in Tree;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
43/5procedure Iterate_Subtree
(Position : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
43.1/5procedure Iterate_Subtree
(Container : in Tree;
Position : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Position)
or else raise Program_Error);
44/5function Iterate (Container : in Tree)
return Tree_Iterator_Interfaces.Parallel_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
45/5function Iterate_Subtree (Position : in Cursor)
return Tree_Iterator_Interfaces.Parallel_Iterator 'Class
with Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
45.1/5function Iterate_Subtree (Container : in Tree; Position : in Cursor)
return Tree_Iterator_Interfaces.Parallel_Iterator'Class
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
46/5function Child_Count (Parent : Cursor) return Count_Type
with Post => (if Parent = No_Element then Child_Count'Result = 0),
with Nonblocking, Global => in all, Use_Formal => null;
46.1/5function Child_Count (Container : Tree; Parent : Cursor)
return Count_Type
with Pre => Meaningful_For (Container, Parent)
or else raise Program_Error,
Post => (if Parent = No_Element then Child_Count'Result = 0),
Nonblocking, Global => null, Use_Formal => null;
47/5function Child_Depth (Parent, Child : Cursor) return Count_Type
with Pre => (Parent = No_Element and then Child = No_Element)
or else raise Constraint_Error,
with Nonblocking, Global => in all, Use_Formal => null;
47.1/5function Child_Depth (Container : Tree; Parent, Child : Cursor)
return Count_Type
with Pre => ((Parent = No_Element and then Child = No_Element)
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Child)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => null;
48/5procedure Insert_Child (Container : in out Tree;
Parent : in Cursor;
Before : in Cursor;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Container.Parent (Before) = Parent
or else raise Constraint_Error),
Post => Node_Count (Container) =
Node_Count (Container)'Old + Count;
49/5procedure Insert_Child (Container : in out Tree;
Parent : in Cursor;
Before : in Cursor;
New_Item : in Element_Type;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Container.Parent (Before) = Parent
or else raise Constraint_Error),
Post => (Node_Count (Container) =
Node_Count (Container)'Old + Count) and then
Has_Element (Container, Position);
50/5procedure Insert_Child (Container : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Container.Parent (Before) = Parent
or else raise Constraint_Error),
Post => (Node_Count (Container) =
Node_Count (Container)'Old + Count) and then
Has_Element (Container, Position);
51/5procedure Prepend_Child (Container : in out Tree;
Parent : in Cursor;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => Node_Count (Container) =
Node_Count (Container)'Old + Count;
52/5procedure Append_Child (Container : in out Tree;
Parent : in Cursor;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => Node_Count (Container) =
Node_Count (Container)'Old + Count;
53/5procedure Delete_Children (Container : in out Tree;
Parent : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => (Node_Count (Container) = Node_Count (Container)'Old -
Child_Count (Container, Parent)'Old) and then
Child_Count (Container, Parent) = 0;
54/5procedure Copy_Subtree (Target : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Source : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Target, Parent)
or else raise Program_Error) and then
(Meaningful_For (Target, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Target.Parent (Before) = Parent
or else raise Constraint_Error) and then
(not Is_Root (Source)
or else raise Constraint_Error),
Post => Node_Count (Target) =
Node_Count (Target)'Old + Subtree_Node_Count (Source),
Global => in all;
54.1/5procedure Copy_Local_Subtree (Target : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Source : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Target, Parent)
or else raise Program_Error) and then
(Meaningful_For (Target, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Target.Parent (Before) = Parent
or else raise Constraint_Error) and then
(Meaningful_For (Target, Source)
or else raise Program_Error) and then
(not Is_Root (Source)
or else raise Constraint_Error),
Post => Node_Count (Target) = Node_Count (Target)'Old +
Subtree_Node_Count (Target, Source);
54.2/5procedure Copy_Subtree (Target : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Source : in Tree;
Subtree : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Target, Parent)
or else raise Program_Error) and then
(Meaningful_For (Target, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Target.Parent (Before) = Parent
or else raise Constraint_Error) and then
(Meaningful_For (Source, Subtree)
or else raise Program_Error) and then
(not Is_Root (Source, Subtree)
or else raise Constraint_Error),
Post => Node_Count (Target) = Node_Count (Target)'Old +
Subtree_Node_Count (Source, Subtree);
55/5procedure Splice_Subtree (Target : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Source : in out Tree;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Target, Parent)
or else raise Program_Error) and then
(Meaningful_For (Target, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Target.Parent (Before) /= Parent
or else raise Constraint_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Source, Position)
or else raise Program_Error) and then
(Target'Has_Same_Storage (Source) or else
Position = Before or else
Is_Ancestor_Of (Target, Position, Parent)
or else raise Constraint_Error),
Post => (declare
Org_Sub_Count renames
Subtree_Node_Count (Source, Position)'Old;
Org_Target_Count renames Node_Count (Target)'Old;
begin
(if not Target'Has_Same_Storage (Source) then
Node_Count (Target) = Org_Target_Count +
Org_Sub_Count and then
Node_Count (Source) = Node_Count (Source)'Old -
Org_Sub_Count and then
Has_Element (Target, Position)
else
Target.Parent (Position) = Parent and then
Node_Count (Target) = Org_Target_Count));
56/5procedure Splice_Subtree (Container: in out Tree;
Parent : in Cursor;
Before : in Cursor;
Position : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Container.Parent (Before) /= Parent
or else raise Constraint_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error) and then
(Position = Before or else
Is_Ancestor_Of (Container, Position, Parent)
or else raise Constraint_Error),
Post => (Node_Count (Container) =
Node_Count (Container)'Old and then
Container.Parent (Position) = Parent);
57/5procedure Splice_Children (Target : in out Tree;
Target_Parent : in Cursor;
Before : in Cursor;
Source : in out Tree;
Source_Parent : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Target_Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Target, Target_Parent)
or else raise Program_Error) and then
(Meaningful_For (Target, Before)
or else raise Program_Error) and then
(Source_Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Source, Source_Parent)
or else raise Program_Error) and then
(Before = No_Element or else
Parent (Target, Before) /= Target_Parent
or else raise Constraint_Error) and then
(Target'Has_Same_Storage (Source) or else
Target_Parent = Source_Parent or else
Is_Ancestor_Of (Target, Source_Parent, Target_Parent)
or else raise Constraint_Error),
Post => (declare
Org_Child_Count renames
Child_Count (Source, Source_Parent)'Old;
Org_Target_Count renames Node_Count (Target)'Old;
begin
(if not Target'Has_Same_Storage (Source) then
Node_Count (Target) = Org_Target_Count +
Org_Child_Count and then
Node_Count (Source) = Node_Count (Source)'Old -
Org_Child_Count
else
Node_Count (Target) = Org_Target_Count));
58/5procedure Splice_Children (Container : in out Tree;
Target_Parent : in Cursor;
Before : in Cursor;
Source_Parent : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Target_Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Target_Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Before)
or else raise Program_Error) and then
(Source_Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Source_Parent)
or else raise Program_Error) and then
(Before = No_Element or else
Parent (Container, Before) /= Target_Parent
or else raise Constraint_Error) and then
(Target_Parent = Source_Parent or else
Is_Ancestor_Of (Container, Source_Parent, Target_Parent)
or else raise Constraint_Error),
Post => Node_Count (Container) = Node_Count (Container)'Old;
59/5function Parent (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element or else
Is_Root (Position) then Parent'Result = No_Element);
59.1/5function Parent (Container : Tree;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element or else
Is_Root (Container, Position)
then Parent'Result = No_Element
else Has_Element (Container, Parent'Result));
60/5function First_Child (Parent : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Pre => Parent /= No_Element or else raise Constraint_Error;
60.1/5function First_Child (Container : Tree;
Parent : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => First_Child'Result = No_Element or else
Has_Element (Container, First_Child'Result);
61/5function First_Child_Element (Parent : Cursor) return Element_Type
with Nonblocking, Global => in all, Use_Formal => Element_Type,
Pre => (Parent /= No_Element and then
Last_Child (Parent) /= No_Element)
or else raise Constraint_Error;
61.1/5function First_Child_Element (Container : Tree;
Parent : Cursor) return Element_Type
with Nonblocking, Global => null, Use_Formal => Element_Type,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(First_Child (Container, Parent) /= No_Element
or else raise Constraint_Error);
62/5function Last_Child (Parent : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Pre => Parent /= No_Element or else raise Constraint_Error;
62.1/5function Last_Child (Container : Tree;
Parent : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => Last_Child'Result = No_Element or else
Has_Element (Container, Last_Child'Result);
63/5function Last_Child_Element (Parent : Cursor) return Element_Type
with Nonblocking, Global => in all, Use_Formal => Element_Type,
Pre => (Parent /= No_Element and then
Last_Child (Parent) /= No_Element)
or else raise Constraint_Error;
63.1/5function Last_Child_Element (Container : Tree;
Parent : Cursor) return Element_Type
with Nonblocking, Global => null, Use_Formal => Element_Type,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Last_Child (Container, Parent) /= No_Element
or else raise Constraint_Error);
64/5function Next_Sibling (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element
then Next_Sibling'Result = No_Element);
64.1/5function Next_Sibling (Container : Tree;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Post => (if Next_Sibling'Result = No_Element then
Position = No_Element or else
Is_Root (Container, Position) or else
Last_Child (Container, Parent (Container, Position))
= Position
else Has_Element (Container, Next_Sibling'Result));
65/5procedure Next_Sibling (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
65.1/5procedure Next_Sibling (Container : in Tree;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
66/5function Previous_Sibling (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element
then Previous_Sibling'Result = No_Element);
66.1/5function Previous_Sibling (Container : Tree;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Post => (if Previous_Sibling'Result = No_Element then
Position = No_Element or else
Is_Root (Container, Position) or else
First_Child (Container, Parent (Container, Position))
= Position
else Has_Element (Container, Previous_Sibling'Result));
67/5procedure Previous_Sibling (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
67.1/5procedure Previous_Sibling (Container : in Tree;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
68/5procedure Iterate_Children
(Parent : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => Parent /= No_Element or else raise Constraint_Error,
Global => in all, Use_Formal => null;
68.1/5procedure Iterate_Children
(Container : in Tree;
Parent : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error);
69/5procedure Reverse_Iterate_Children
(Parent : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => Parent /= No_Element or else raise Constraint_Error,
Global => in all, Use_Formal => null;
69.1/5procedure Reverse_Iterate_Children
(Container : in Tree;
Parent : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error);
70/5function Iterate_Children (Container : in Tree; Parent : in Cursor)
return Tree_Iterator_Interfaces.Parallel_Reversible_Iterator 'Class
with Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
70.1/5package Stable is
70.2/5type Tree (Base : not null access Multiway_Trees.Tree) is
tagged limited private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type,
Stable_Properties => (Node_Count),
Global => null,
Default_Initial_Condition => Node_Count (Tree) = 1,
Preelaborable_Initialization;
70.3/5type Cursor is private
with Preelaborable_Initialization;
70.4/5Empty_Tree : constant Tree;
70.5/5No_Element : constant Cursor;
70.6/5function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
70.7/5package Tree_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
70.8/5procedure Assign (Target : in out Multiway_Trees.Tree;
Source : in Tree)
with Post => Node_Count (Source) = Node_Count (Target);
70.9/5function Copy (Source : Multiway_Trees.Tree) return Tree
with Post => Node_Count (Copy'Result) = Node_Count (Source);
70.10/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null,
Default_Initial_Condition => (raise Program_Error);
70.11/5type Reference_Type
(Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => null,
Default_Initial_Condition => (raise Program_Error);
70.12/5-- Additional subprograms as described in the text
-- are declared here.
70.13/5private
70.14/5... -- not specified by the language
70.15/5end Stable;
71/3private
... -- not specified by the language
end Ada.Containers.Multiway_Trees;
The actual function for the generic formal function "=" on Element_Type values is expected to define a reflexive and symmetric relationship and return the same result value each time it is called with a particular pair of values. If it behaves in some other manner, the functions Find, Reverse_Find, Equal_Subtree, and "=" on tree values return an unspecified value. The exact arguments and number of calls of this generic formal function by the functions Find, Reverse_Find, Equal_Subtree, and "=" on tree values are unspecified.
The type Tree is used to represent trees. The type Tree needs finalization (see 7.6).
Empty_Tree represents the empty Tree object. It contains only the root node (Node_Count (Empty_Tree) returns 1). If an object of type Tree is not otherwise initialized, it is initialized to the same value as Empty_Tree.
No_Element represents a cursor that designates no element. If an object of type Cursor is not otherwise initialized, it is initialized to the same value as No_Element.
The primitive "=" operator for type Cursor returns True if both cursors are No_Element, or designate the same element in the same container.
Execution of the default implementation of the Input, Output, Read, or Write attribute of type Cursor raises Program_Error.
Tree'Write for a Tree object T writes Node_Count(T) - 1 elements of the tree to the stream. It may also write additional information about the tree.
Tree'Read reads the representation of a tree from the stream, and assigns to Item a tree with the same elements and structure as was written by Tree'Write.
[Some operations check for “tampering with cursors” of a container because they depend on the set of elements of the container remaining constant, and others check for “tampering with elements” of a container because they depend on elements of the container not being replaced.] When tampering with cursors is prohibited for a particular tree object T, Program_Error is propagated by the finalization of T[, as well as by a call that passes T to certain of the operations of this package, as indicated by the precondition of such an operation]. Similarly, when tampering with elements is prohibited for T, Program_Error is propagated by a call that passes T to certain of the other operations of this package, as indicated by the precondition of such an operation.
Paragraphs 81 through 90 are removed as preconditions now describe these rules.
assignment_statement, because that finalizes the target object as part of the operation, and finalization of an object is already defined as tampering with cursors.
function Has_Element (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
Returns True if Position designates an element, and returns False otherwise. [In particular, Has_Element returns False if the cursor designates a root node or equals No_Element.]
function Has_Element (Container : Tree; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if Position designates an element in Container, and returns False otherwise. [In particular, Has_Element returns False if the cursor designates a root node or equals No_Element.]
function Equal_Subtree (Left_Position : Cursor;
Right_Position: Cursor) return Boolean;
If Left_Position or Right_Position equals No_Element, propagates Constraint_Error. If the number of child nodes of the element designated by Left_Position is different from the number of child nodes of the element designated by Right_Position, the function returns False. If Left_Position designates a root node and Right_Position does not, the function returns False. If Right_Position designates a root node and Left_Position does not, the function returns False. Unless both cursors designate a root node, the elements are compared using the generic formal equality operator. If the result of the element comparison is False, the function returns False. Otherwise, it calls Equal_Subtree on a cursor designating each child element of the element designated by Left_Position and a cursor designating the corresponding child element of the element designated by Right_Position. If any such call returns False, the function returns False; otherwise, it returns True. Any exception raised during the evaluation of element equality is propagated.
function "=" (Left, Right : Tree) return Boolean;
If Left and Right denote the same tree object, then the function returns True. Otherwise, it calls Equal_Subtree with cursors designating the root nodes of Left and Right; the result is returned. Any exception raised during the evaluation of Equal_Subtree is propagated.
function Tampering_With_Cursors_Prohibited
(Container : Tree) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if tampering with cursors or tampering with elements is currently prohibited for Container, and returns False otherwise.
function Tampering_With_Elements_Prohibited
(Container : Tree) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Always returns False[, regardless of whether tampering with elements is prohibited].
function Is_Empty (Container : Tree) return Boolean
with Nonblocking, Global => null, Use_Formal => null,
Post => Is_Empty'Result = (Node_Count (Container) = 1);
Returns True if Container is empty.
function Node_Count (Container : Tree) return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
Node_Count returns the number of nodes in Container.
function Subtree_Node_Count (Position : Cursor) return Count_Type
with Nonblocking, Global => in all, Use_Formal => null);
If Position is No_Element, Subtree_Node_Count returns 0; otherwise, Subtree_Node_Count returns the number of nodes in the subtree that is rooted by Position.
function Subtree_Node_Count (Container : Tree; Position : Cursor)
return Count_Type
with Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Nonblocking, Global => null, Use_Formal => null ;
If Position is No_Element, Subtree_Node_Count returns 0; otherwise, Subtree_Node_Count returns the number of nodes in the subtree of Container that is rooted by Position .
function Depth (Position : Cursor) return Count_Type
with Nonblocking, Global => in all, Use_Formal => null;
If Position equals No_Element, Depth returns 0; otherwise, Depth returns the number of ancestor nodes of the node designated by Position (including the node itself).
function Depth (Container : Tree; Position : Cursor)
return Count_Type
with Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Nonblocking, Global => null, Use_Formal => null;
If Position equals No_Element, Depth returns 0; otherwise, Depth returns the number of ancestor nodes of the node of Container designated by Position (including the node itself).
function Is_Root (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
Is_Root returns True if the Position designates the root node of some tree; and returns False otherwise.
function Is_Root (Container : Tree; Position : Cursor)
return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Is_Root returns True if the Position designates the root node of Container; and returns False otherwise.
function Is_Leaf (Position : Cursor) return Boolean
with Nonblocking, Global => in all, Use_Formal => null;
Is_Leaf returns True if Position designates a node that does not have any child nodes; and returns False otherwise.
function Is_Leaf (Container : Tree; Position : Cursor)
return Boolean
with Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Nonblocking, Global => null, Use_Formal => null;
Is_Leaf returns True if Position designates a node in Container that does not have any child nodes; and returns False otherwise.
function Is_Ancestor_Of (Container : Tree;
Parent : Cursor;
Position : Cursor) return Boolean
with Pre => (Meaningful_For (Container, Position)
or else raise Program_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => null;
Is_Ancestor_Of returns True if Parent designates an ancestor node of Position (including Position itself), and returns False otherwise.
function Root (Container : Tree) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Post => Root'Result /= No_Element and then
not Has_Element (Container, Root'Result);
Root returns a cursor that designates the root node of Container.
procedure Clear (Container : in out Tree)
with Pre => not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error,
Post => Node_Count (Container) = 1;
Removes all the elements from Container.
function Element (Position : Cursor) return Element_Type
with Pre => (Position /= No_Element or else
raise Constraint_Error) and then
(Has_Element (Position) or else raise Program_Error),
Nonblocking, Global => in all, Use_Formal => Element_Type;
Element returns the element designated by Position.
function Element (Container : Tree;
Position : Cursor) return Element_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => Element_Type;
Element returns the element designated by Position in Container.
procedure Replace_Element (Container : in out Tree;
Position : in Cursor;
New_item : in Element_Type)
with Pre => (not Tampering_With_Elements_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Replace_Element assigns the value New_Item to the element designated by Position. For the purposes of determining whether the parameters overlap in a call to Replace_Element, the Container parameter is not considered to overlap with any object [(including itself)].
procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Position)
or else raise Program_Error),
Global => in all;
Query_Element calls Process.all with the element designated by Position as the argument. Tampering with the elements of the tree that contains the element designated by Position is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Query_Element
(Container : in Tree;
Position : in Cursor;
Process : not null access procedure (Element : in Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Query_Element calls Process.all with the element designated by Position as the argument. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Update_Element
(Container : in out Tree;
Position : in Cursor;
Process : not null access procedure
(Element : in out Element_Type))
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error);
Update_Element calls Process.all with the element designated by Position as the argument. Tampering with the elements of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
If Element_Type is unconstrained and definite, then the actual Element parameter of Process.all shall be unconstrained.
type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
122/5type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
The types Constant_Reference_Type and Reference_Type need finalization.
This paragraph was deleted.
function Constant_Reference (Container : aliased in Tree;
Position : in Cursor)
return Constant_Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Constant_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read access to an individual element of a tree given a cursor.
Constant_Reference returns an object whose discriminant is an access value that designates the element designated by Position. Tampering with the elements of Container is prohibited while the object returned by Constant_Reference exists and has not been finalized.
function Reference (Container : aliased in out Tree;
Position : in Cursor)
return Reference_Type
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Variable_Indexing and Implicit_Dereference aspects) provides a convenient way to gain read and write access to an individual element of a tree given a cursor.
Reference returns an object whose discriminant is an access value that designates the element designated by Position. Tampering with the elements of Container is prohibited while the object returned by Reference exists and has not been finalized.
procedure Assign (Target : in out Tree; Source : in Tree)
with Pre => not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error,
Post => Node_Count (Source) = Node_Count (Target);
If Target denotes the same object as Source, the operation has no effect. Otherwise, the elements of Source are copied to Target as for an assignment_statement assigning Source to Target.
function Copy (Source : Tree) return Tree
with Post =>
Node_Count (Copy'Result) = Node_Count (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result);
Returns a tree with the same structure as Source and whose elements are initialized from the corresponding elements of Source.
procedure Move (Target : in out Tree;
Source : in out Tree)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Node_Count (Target) = Node_Count (Source'Old) and then
Node_Count (Source) = 1);
If Target denotes the same object as Source, then the operation has no effect. Otherwise, Move first calls Clear (Target). Then, the nodes other than the root node in Source are moved to Target (in the same positions). After Move completes, Node_Count (Target) is the number of nodes originally in Source, and Node_Count (Source) is 1.
procedure Delete_Leaf (Container : in out Tree;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error) and then
(Is_Leaf (Container, Position)
or else raise Constraint_Error),
Post =>
Node_Count (Container)'Old = Node_Count (Container) + 1 and then
Position = No_Element;
Delete_Leaf removes (from Container) the element designated by Position, and Position is set to No_Element.
procedure Delete_Subtree (Container : in out Tree;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error),
Post => Node_Count (Container)'Old = Node_Count (Container) +
Subtree_Node_Count (Container, Position)'Old and then
Position = No_Element;
Delete_Subtree removes (from Container) the subtree designated by Position (that is, all descendants of the node designated by Position including the node itself), and Position is set to No_Element.
procedure Swap (Container : in out Tree;
I, J : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(I /= No_Element or else Constraint_Error) and then
(J /= No_Element or else Constraint_Error) and then
(Has_Element (Container, I)
or else raise Program_Error) and then
(Has_Element (Container, J)
or else raise Program_Error);
Swap exchanges the values of the elements designated by I and J.
function Find (Container : Tree;
Item : Element_Type)
return Cursor
with Post => (if Find'Result /= No_Element
then Has_Element (Container, Find'Result));
Find searches the elements of Container for an element equal to Item (using the generic formal equality operator). The search starts at the root node. The search traverses the tree in a depth-first order. If no equal element is found, then Find returns No_Element. Otherwise, it returns a cursor designating the first equal element encountered.
function Find_In_Subtree (Position : Cursor;
Item : Element_Type)
return Cursor
with Pre => Position /= No_Element or else raise Constraint_Error,
Post => (if Find_In_Subtree'Result = No_Element
then Has_Element (Find_In_Subtree'Result)),
Global => in all;
Find_In_Subtree searches the subtree rooted by Position for an element equal to Item (using the generic formal equality operator). The search starts at the element designated by Position. The search traverses the subtree in a depth-first order. If no equal element is found, then Find returns No_Element. Otherwise, it returns a cursor designating the first equal element encountered.
function Find_In_Subtree (Container : Tree;
Position : Cursor;
Item : Element_Type)
return Cursor
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Position)
or else raise Program_Error),
Post => (if Find_In_Subtree'Result = No_Element
then Has_Element (Container, Find_In_Subtree'Result));
Find_In_Subtree searches the subtree of Container rooted by Position for an element equal to Item (using the generic formal equality operator). The search starts at the element designated by Position. The search traverses the subtree in a depth-first order. If no equal element is found, then Find returns No_Element. Otherwise, it returns a cursor designating the first equal element encountered.
function Ancestor_Find (Position : Cursor;
Item : Element_Type)
return Cursor
with Pre => Position /= No_Element or else raise Constraint_Error,
Post => (if Ancestor_Find'Result = No_Element
then Has_Element (Container, Ancestor_Find'Result)),
Global => in all;
Ancestor_Find searches for an element equal to Item (using the generic formal equality operator). The search starts at the node designated by Position, and checks each ancestor proceeding toward the root of the subtree. If no equal element is found, then Ancestor_Find returns No_Element. Otherwise, it returns a cursor designating the first equal element encountered.
function Ancestor_Find (Container : Tree;
Position : Cursor;
Item : Element_Type)
return Cursor
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Position)
or else raise Program_Error),
Post => (if Ancestor_Find'Result = No_Element
then Has_Element (Container, Ancestor_Find'Result));
Ancestor_Find searches for an element equal to Item (using the generic formal equality operator). The search starts at the node designated by Position in Container, and checks each ancestor proceeding toward the root of the subtree. If no equal element is found, then Ancestor_Find returns No_Element. Otherwise, it returns a cursor designating the first equal element encountered.
function Contains (Container : Tree;
Item : Element_Type) return Boolean;
Equivalent to Find (Container, Item) /= No_Element.
procedure Iterate
(Container : in Tree;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit;
Iterate calls Process.all with a cursor that designates each element in Container, starting from the root node and proceeding in a depth-first order. Tampering with the cursors of Container is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
procedure Iterate_Subtree
(Position : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
Iterate_Subtree calls Process.all with a cursor that designates each element in the subtree rooted by the node designated by Position, starting from the node designated by Position and proceeding in a depth-first order. Tampering with the cursors of the tree that contains the element designated by Position is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
procedure Iterate_Subtree
(Container : in Tree;
Position : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Position)
or else raise Program_Error);
Iterate_Subtree calls Process.all with a cursor that designates each element in the subtree rooted by the node designated by Position in Container, starting from the node designated by Position and proceeding in a depth-first order. Tampering with the cursors of the tree that contains the element designated by Position is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
function Iterate (Container : in Tree)
return Tree_Iterator_Interfaces.Parallel_Iterator 'Class
with Post => Tampering_With_Cursors_Prohibited (Container);
Iterate returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each element in Container, starting from the root node and proceeding in a depth-first order when used as a forward iterator, and processing all nodes concurrently when used as a parallel iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
exit when Cur = Stop;
function Iterate_Subtree (Position : in Cursor)
return Tree_Iterator_Interfaces.Parallel_Iterator 'Class
with Pre => Position /= No_Element or else raise Constraint_Error,
Global => in all;
Iterate_Subtree returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each element in the subtree rooted by the node designated by Position, starting from the node designated by Position and proceeding in a depth-first order when used as a forward iterator, and processing all nodes in the subtree concurrently when used as a parallel iterator. Tampering with the cursors of the container that contains the node designated by Position is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
function Iterate_Subtree (Container : in Tree; Position : in Cursor)
return Tree_Iterator_Interfaces.Parallel_Iterator'Class
with Pre => (Position /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Position)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
Iterate_Subtree returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each element in the subtree rooted by the node designated by Position in Container, starting from the node designated by Position and proceeding in a depth-first order when used as a forward iterator, and processing all nodes in the subtree concurrently when used as a parallel iterator. Tampering with the cursors of the container that contains the node designated by Position is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
function Child_Count (Parent : Cursor) return Count_Type
with Post => (if Parent = No_Element then Child_Count'Result = 0),
Nonblocking, Global => in all, Use_Formal => null;
Child_Count returns the number of child nodes of the node designated by Parent.
function Child_Count (Container : Tree; Parent : Cursor)
return Count_Type
with Pre => Meaningful_For (Container, Parent)
or else raise Program_Error,
Post => (if Parent = No_Element then Child_Count'Result = 0),
Nonblocking, Global => null, Use_Formal => null;
Child_Count returns the number of child nodes of the node designated by Parent in Container.
function Child_Depth (Parent, Child : Cursor) return Count_Type
with Pre => (Parent /= No_Element and then Child /= No_Element)
or else raise Constraint_Error,
Nonblocking, Global => in all, Use_Formal => null;
Child_Depth returns the number of ancestor nodes of Child (including Child itself), up to but not including Parent; Program_Error is propagated if Parent is not an ancestor of Child.
function Child_Depth (Container : Tree; Parent, Child : Cursor)
return Count_Type
with Pre => ((Parent /= No_Element and then Child /= No_Element)
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Child)
or else raise Program_Error),
Nonblocking, Global => null, Use_Formal => null;
Child_Depth returns the number of ancestor nodes of Child within Container (including Child itself), up to but not including Parent; Program_Error is propagated if Parent is not an ancestor of Child.
procedure Insert_Child (Container : in out Tree;
Parent : in Cursor;
Before : in Cursor;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Container.Parent (Before) = Parent
or else raise Constraint_Error),
Post => Node_Count (Container) =
Node_Count (Container)'Old + Count;
Insert_Child allocates Count nodes containing copies of New_Item and inserts them as children of Parent. If Parent already has child nodes, then the new nodes are inserted prior to the node designated by Before, or, if Before equals No_Element, the new nodes are inserted after the last existing child node of Parent. Any exception raised during allocation of internal storage is propagated, and Container is not modified.
procedure Insert_Child (Container : in out Tree;
Parent : in Cursor;
Before : in Cursor;
New_Item : in Element_Type;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Container.Parent (Before) = Parent
or else raise Constraint_Error),
Post => (Node_Count (Container) =
Node_Count (Container)'Old + Count) and then
Has_Element (Container, Position);
Insert_Child allocates Count nodes containing copies of New_Item and inserts them as children of Parent. If Parent already has child nodes, then the new nodes are inserted prior to the node designated by Before, or, if Before equals No_Element, the new nodes are inserted after the last existing child node of Parent. Position designates the first newly-inserted node, or if Count equals 0, then Position is assigned the value of Before. Any exception raised during allocation of internal storage is propagated, and Container is not modified.
procedure Insert_Child (Container : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Container.Parent (Before) = Parent
or else raise Constraint_Error),
Post => (Node_Count (Container) =
Node_Count (Container)'Old + Count) and then
Has_Element (Container, Position);
Insert_Child allocates Count nodes, the elements contained in the new nodes are initialized by default (see 3.3.1), and the new nodes are inserted as children of Parent. If Parent already has child nodes, then the new nodes are inserted prior to the node designated by Before, or, if Before equals No_Element, the new nodes are inserted after the last existing child node of Parent. Position designates the first newly-inserted node, or if Count equals 0, then Position is assigned the value of Before. Any exception raised during allocation of internal storage is propagated, and Container is not modified.
procedure Prepend_Child (Container : in out Tree;
Parent : in Cursor;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => Node_Count (Container) =
Node_Count (Container)'Old + Count;
Equivalent to Insert_Child (Container, Parent, First_Child (Container, Parent), New_Item, Count).
procedure Append_Child (Container : in out Tree;
Parent : in Cursor;
New_Item : in Element_Type;
Count : in Count_Type := 1)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => Node_Count (Container) =
Node_Count (Container)'Old + Count;
Equivalent to Insert_Child (Container, Parent, No_Element, New_Item, Count).
procedure Delete_Children (Container : in out Tree;
Parent : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => (Node_Count (Container) = Node_Count (Container)'Old -
Child_Count (Container, Parent)'Old) and then
Child_Count (Container, Parent) = 0;
Delete_Children removes (from Container) all of the descendants of Parent other than Parent itself.
procedure Copy_Subtree (Target : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Source : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Target, Parent)
or else raise Program_Error) and then
(Meaningful_For (Target, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Target.Parent (Before) = Parent
or else raise Constraint_Error) and then
(not Is_Root (Source)
or else raise Constraint_Error),
Post => Node_Count (Target) =
Node_Count (Target)'Old + Subtree_Node_Count (Source),
Global => in all;
If Source is equal to No_Element, then the operation has no effect. Otherwise, the subtree rooted by Source (which can be from any tree; it does not have to be a subtree of Target) is copied (new nodes are allocated to create a new subtree with the same structure as the Source subtree, with each element initialized from the corresponding element of the Source subtree) and inserted into Target as a child of Parent. If Parent already has child nodes, then the new nodes are inserted prior to the node designated by Before, or, if Before equals No_Element, the new nodes are inserted after the last existing child node of Parent. The parent of the newly created subtree is set to Parent, and the overall count of Target is incremented by Subtree_Node_Count (Source). Any exception raised during allocation of internal storage is propagated, and Container is not modified.
procedure Copy_Local_Subtree (Target : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Source : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Target, Parent)
or else raise Program_Error) and then
(Meaningful_For (Target, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Target.Parent (Before) = Parent
or else raise Constraint_Error) and then
(Meaningful_For (Target, Source)
or else raise Program_Error) and then
(not Is_Root (Source)
or else raise Constraint_Error),
Post => Node_Count (Target) = Node_Count (Target)'Old +
Subtree_Node_Count (Target, Source);
If Source is equal to No_Element, then the operation has no effect. Otherwise, the subtree rooted by Source in Target is copied (new nodes are allocated to create a new subtree with the same structure as the Source subtree, with each element initialized from the corresponding element of the Source subtree) and inserted into Target as a child of Parent. If Parent already has child nodes, then the new nodes are inserted prior to the node designated by Before, or, if Before equals No_Element, the new nodes are inserted after the last existing child node of Parent. The parent of the newly created subtree is set to Parent. Any exception raised during allocation of internal storage is propagated, and Container is not modified.
procedure Copy_Subtree (Target : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Source : in Tree;
Subtree : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Target, Parent)
or else raise Program_Error) and then
(Meaningful_For (Target, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Target.Parent (Before) = Parent
or else raise Constraint_Error) and then
(Meaningful_For (Source, Subtree)
or else raise Program_Error) and then
(not Is_Root (Source, Subtree)
or else raise Constraint_Error),
Post => Node_Count (Target) = Node_Count (Target)'Old +
Subtree_Node_Count (Source, Subtree);
If Subtree is equal to No_Element, then the operation has no effect. Otherwise, the subtree rooted by Subtree in Source is copied (new nodes are allocated to create a new subtree with the same structure as the Subtree, with each element initialized from the corresponding element of the Subtree) and inserted into Target as a child of Parent. If Parent already has child nodes, then the new nodes are inserted prior to the node designated by Before, or, if Before equals No_Element, the new nodes are inserted after the last existing child node of Parent. The parent of the newly created subtree is set to Parent. Any exception raised during allocation of internal storage is propagated, and Container is not modified.
procedure Splice_Subtree (Target : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Source : in out Tree;
Position : in out Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Target, Parent)
or else raise Program_Error) and then
(Meaningful_For (Target, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Target.Parent (Before) /= Parent
or else raise Constraint_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Source, Position)
or else raise Program_Error) and then
(Target'Has_Same_Storage (Source) or else
Position = Before or else
Is_Ancestor_Of (Target, Position, Parent)
or else raise Constraint_Error),
Post => (declare
Org_Sub_Count renames
Subtree_Node_Count (Source, Position)'Old;
Org_Target_Count renames Node_Count (Target)'Old;
begin
(if not Target'Has_Same_Storage (Source) then
Node_Count (Target) = Org_Target_Count +
Org_Sub_Count and then
Node_Count (Source) = Node_Count (Source)'Old -
Org_Sub_Count and then
Has_Element (Target, Position)
else
Target.Parent (Position) = Parent and then
Node_Count (Target) = Org_Target_Count));
If Source denotes the same object as Target, then: if Position equals Before there is no effect; otherwise, the subtree rooted by the element designated by Position is moved to be a child of Parent. If Parent already has child nodes, then the moved nodes are inserted prior to the node designated by Before, or, if Before equals No_Element, the moved nodes are inserted after the last existing child node of Parent. In each of these cases, Position and the count of Target are unchanged, and the parent of the element designated by Position is set to Parent.
Otherwise (if Source does not denote the same object as Target), the subtree designated by Position is removed from Source and moved to Target. The subtree is inserted as a child of Parent. If Parent already has child nodes, then the moved nodes are inserted prior to the node designated by Before, or, if Before equals No_Element, the moved nodes are inserted after the last existing child node of Parent. In each of these cases, the count of Target is incremented by Subtree_Node_Count (Position), and the count of Source is decremented by Subtree_Node_Count (Position), Position is updated to represent an element in Target.
procedure Splice_Subtree (Container: in out Tree;
Parent : in Cursor;
Before : in Cursor;
Position : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Before)
or else raise Program_Error) and then
(Before = No_Element or else
Container.Parent (Before) /= Parent
or else raise Constraint_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Container, Position)
or else raise Program_Error) and then
(Position = Before or else
Is_Ancestor_Of (Container, Position, Parent)
or else raise Constraint_Error),
Post => (Node_Count (Container) =
Node_Count (Container)'Old and then
Container.Parent (Position) = Parent);
If Position equals Before, there is no effect. Otherwise, the subtree rooted by the element designated by Position is moved to be a child of Parent. If Parent already has child nodes, then the moved nodes are inserted prior to the node designated by Before, or, if Before equals No_Element, the moved nodes are inserted after the last existing child node of Parent. The parent of the element designated by Position is set to Parent.
procedure Splice_Children (Target : in out Tree;
Target_Parent : in Cursor;
Before : in Cursor;
Source : in out Tree;
Source_Parent : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Target_Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Target, Target_Parent)
or else raise Program_Error) and then
(Meaningful_For (Target, Before)
or else raise Program_Error) and then
(Source_Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Source, Source_Parent)
or else raise Program_Error) and then
(Before = No_Element or else
Parent (Target, Before) /= Target_Parent
or else raise Constraint_Error) and then
(Target'Has_Same_Storage (Source) or else
Target_Parent = Source_Parent or else
Is_Ancestor_Of (Target, Source_Parent, Target_Parent)
or else raise Constraint_Error),
Post => (declare
Org_Child_Count renames
Child_Count (Source, Source_Parent)'Old;
Org_Target_Count renames Node_Count (Target)'Old;
begin
(if not Target'Has_Same_Storage (Source) then
Node_Count (Target) = Org_Target_Count +
Org_Child_Count and then
Node_Count (Source) = Node_Count (Source)'Old -
Org_Child_Count
else
Node_Count (Target) = Org_Target_Count));
This paragraph was deleted.
If Source denotes the same object as Target, then:
- if Target_Parent equals Source_Parent there is no effect; else
- This paragraph was deleted.
- the child elements (and the further descendants) of Source_Parent are moved to be child elements of Target_Parent. If Target_Parent already has child elements, then the moved elements are inserted prior to the node designated by Before, or, if Before equals No_Element, the moved elements are inserted after the last existing child node of Target_Parent. The parent of each moved child element is set to Target_Parent.
Otherwise (if Source does not denote the same object as Target), the child elements (and the further descendants) of Source_Parent are removed from Source and moved to Target. The child elements are inserted as children of Target_Parent. If Target_Parent already has child elements, then the moved elements are inserted prior to the node designated by Before, or, if Before equals No_Element, the moved elements are inserted after the last existing child node of Target_Parent. In each of these cases, the overall count of Target is incremented by Subtree_Node_Count (Source_Parent)-1, and the overall count of Source is decremented by Subtree_Node_Count (Source_Parent)-1.
procedure Splice_Children (Container : in out Tree;
Target_Parent : in Cursor;
Before : in Cursor;
Source_Parent : in Cursor)
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Target_Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Target_Parent)
or else raise Program_Error) and then
(Meaningful_For (Container, Before)
or else raise Program_Error) and then
(Source_Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Source_Parent)
or else raise Program_Error) and then
(Before = No_Element or else
Parent (Container, Before) /= Target_Parent
or else raise Constraint_Error) and then
(Target_Parent = Source_Parent or else
Is_Ancestor_Of (Container, Source_Parent, Target_Parent)
or else raise Constraint_Error),
Post => Node_Count (Container) = Node_Count (Container)'Old;
If Target_Parent equals Source_Parent there is no effect. Otherwise, the child elements (and the further descendants) of Source_Parent are moved to be child elements of Target_Parent. If Target_Parent already has child elements, then the moved elements are inserted prior to the node designated by Before, or, if Before equals No_Element, the moved elements are inserted after the last existing child node of Target_Parent. The parent of each moved child element is set to Target_Parent.
function Parent (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element or else
Is_Root (Position) then Parent'Result = No_Element);
Returns a cursor designating the parent node of the node designated by Position .
function Parent (Container : Tree;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Post => (if Position = No_Element or else
Is_Root (Container, Position)
then Parent'Result = No_Element
else Has_Element (Container, Parent'Result));
Returns a cursor designating the parent node of the node designated by Position in Container.
function First_Child (Parent : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Pre => Parent /= No_Element or else raise Constraint_Error;
First_Child returns a cursor designating the first child node of the node designated by Parent; if there is no such node, No_Element is returned.
function First_Child (Container : Tree;
Parent : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => First_Child'Result = No_Element or else
Has_Element (Container, First_Child'Result);
First_Child returns a cursor designating the first child node of the node designated by Parent in Container; if there is no such node, No_Element is returned.
function First_Child_Element (Parent : Cursor) return Element_Type
with Nonblocking, Global => in all, Use_Formal => Element_Type,
Pre => (Parent /= No_Element and then
Last_Child (Parent) /= No_Element)
or else raise Constraint_Error;
Equivalent to Element (First_Child (Parent)).
function First_Child_Element (Container : Tree;
Parent : Cursor) return Element_Type
with Nonblocking, Global => null, Use_Formal => Element_Type,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(First_Child (Container, Parent) /= No_Element
or else raise Constraint_Error);
Equivalent to Element (Container, First_Child (Container, Parent)).
function Last_Child (Parent : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Pre => Parent /= No_Element or else raise Constraint_Error;
Last_Child returns a cursor designating the last child node of the node designated by Parent; if there is no such node, No_Element is returned.
function Last_Child (Container : Tree;
Parent : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => Last_Child'Result = No_Element or else
Has_Element (Container, Last_Child'Result);
Last_Child returns a cursor designating the last child node of the node designated by Parent in Container; if there is no such node, No_Element is returned.
function Last_Child_Element (Parent : Cursor) return Element_Type
with Nonblocking, Global => in all, Use_Formal => Element_Type,
Pre => (Parent /= No_Element and then
Last_Child (Parent) /= No_Element)
or else raise Constraint_Error;
Equivalent to Element (Last_Child (Parent)).
function Last_Child_Element (Container : Tree;
Parent : Cursor) return Element_Type
with Nonblocking, Global => null, Use_Formal => Element_Type,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error) and then
(Last_Child (Container, Parent) /= No_Element
or else raise Constraint_Error);
Equivalent to Element (Container, Last_Child (Container, Parent)).
function Next_Sibling (Position : Cursor) return Cursor
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element
then Next_Sibling'Result = No_Element);
If Position equals No_Element or designates the last child node of its parent, then Next_Sibling returns the value No_Element. Otherwise, it returns a cursor that designates the successor (with the same parent) of the node designated by Position.
function Next_Sibling (Container : Tree;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Post => (if Next_Sibling'Result = No_Element then
Position = No_Element or else
Is_Root (Container, Position) or else
Last_Child (Container, Parent (Container, Position))
= Position
else Has_Element (Container, Next_Sibling'Result));
Next_Sibling returns a cursor that designates the successor (with the same parent) of the node designated by Position in Container.
function Previous_Sibling (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null,
Post => (if Position = No_Element
then Previous_Sibling'Result = No_Element);
If Position equals No_Element or designates the first child node of its parent, then Previous_Sibling returns the value No_Element. Otherwise, it returns a cursor that designates the predecessor (with the same parent) of the node designated by Position.
function Previous_Sibling (Container : Tree;
Position : Cursor) return Cursor
with Nonblocking, Global => null, Use_Formal => null,
Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Post => (if Previous_Sibling'Result = No_Element then
Position = No_Element or else
Is_Root (Container, Position) or else
First_Child (Container, Parent (Container, Position))
= Position
else Has_Element (Container, Previous_Sibling'Result));
Previous_Sibling returns a cursor that designates the predecessor (with the same parent) of the node designated by Position in Container.
procedure Next_Sibling (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
Equivalent to Position := Next_Sibling (Position);
procedure Next_Sibling (Container : in Tree;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position));
Equivalent to Position := Next_Sibling (Container, Position);
procedure Previous_Sibling (Position : in out Cursor)
with Nonblocking, Global => in all, Use_Formal => null;
Equivalent to Position := Previous_Sibling (Position);
procedure Previous_Sibling (Container : in Tree;
Position : in out Cursor)
with Nonblocking, Global => null, Use_Formal => null,
Pre => Meaningful_For (Container, Position)
or else raise Program_Error,
Post => (if Position /= No_Element
then Has_Element (Container, Position);
Equivalent to Position := Previous_Sibling (Container, Position);
procedure Iterate_Children
(Parent : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => Parent /= No_Element or else raise Constraint_Error,
Global => in all, Use_Formal => null;
This paragraph was deleted.
Iterate_Children calls Process.all with a cursor that designates each child node of Parent, starting with the first child node and moving the cursor as per the Next_Sibling function.
Tampering with the cursors of the tree containing Parent is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
procedure Iterate_Children
(Container : in Tree;
Parent : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error);
Iterate_Children calls Process.all with a cursor that designates each child node of Container and Parent, starting with the first child node and moving the cursor as per the Next_Sibling function.
Tampering with the cursors of the tree containing Parent is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
procedure Reverse_Iterate_Children
(Parent : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => Parent /= No_Element or else raise Constraint_Error,
Global => in all, Use_Formal => null;
This paragraph was deleted.
Reverse_Iterate_Children calls Process.all with a cursor that designates each child node of Parent, starting with the last child node and moving the cursor as per the Previous_Sibling function.
Tampering with the cursors of the tree containing Parent is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
procedure Reverse_Iterate_Children
(Container : in Tree;
Parent : in Cursor;
Process : not null access procedure (Position : in Cursor))
with Allows_Exit,
Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error);
Reverse_Iterate_Children calls Process.all with a cursor that designates each child node of Container and Parent, starting with the last child node and moving the cursor as per the Previous_Sibling function.
Tampering with the cursors of the tree containing Parent is prohibited during the execution of a call on Process.all. Any exception raised by Process.all is propagated.
function Iterate_Children (Container : in Tree; Parent : in Cursor)
return Tree_Iterator_Interfaces.Parallel_Reversible_Iterator 'Class
with Pre => (Parent /= No_Element
or else raise Constraint_Error) and then
(Meaningful_For (Container, Parent)
or else raise Program_Error),
Post => Tampering_With_Cursors_Prohibited (Container);
Iterate_Children returns an iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each child node of Parent. When used as a forward iterator, the nodes are designated starting with the first child node and moving the cursor as per the function Next_Sibling; when used as a reverse iterator, the nodes are designated starting with the last child node and moving the cursor as per the function Previous_Sibling; when used as a parallel iterator, processing all child nodes concurrently. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
The nested package Multiway_Trees.Stable provides a type Stable.Tree that represents a stable tree, which is one that cannot grow and shrink. Such a tree can be created by calling the Copy function, or by establishing a stabilized view of an ordinary tree.
The subprograms of package Containers.Multiway_Trees that have a parameter or result of type tree are included in the nested package Stable with the same specification, except that the following are omitted:
Tampering_With_Cursors_Prohibited, Tampering_With_Elements_Prohibited, Assign, Move, Clear, Delete_Leaf, Insert_Child, Delete_Children, Delete_Subtree, Copy_Subtree, Copy_Local_Subtree, Splice_Subtree, and Splice_Children
The operations of this package are equivalent to those for ordinary trees, except that the calls to Tampering_With_Cursors_Prohibited and Tampering_With_Elements_Prohibited that occur in preconditions are replaced by False, and any that occur in postconditions are replaced by True.
If a stable tree is declared with the Base discriminant designating a pre-existing ordinary tree, the stable tree represents a stabilized view of the underlying ordinary tree, and any operation on the stable tree is reflected on the underlying ordinary tree. While a stabilized view exists, any operation that tampers with elements performed on the underlying tree is prohibited. The finalization of a stable tree that provides such a view removes this restriction on the underlying ordinary tree [(though some other restriction can exist due to other concurrent iterations or stabilized views)].
If a stable tree is declared without specifying Base, the object is necessarily initialized. The initializing expression of the stable tree, [typically a call on Copy], determines the Node_Count of the tree. The Node_Count of a stable tree never changes after initialization.
Bounded (Run-Time) Errors
219/3It is a bounded error for the actual function associated with a generic formal subprogram, when called as part of an operation of this package, to tamper with elements of any Tree parameter of the operation. Either Program_Error is raised, or the operation works as defined on the value of the Tree either prior to, or subsequent to, some or all of the modifications to the Tree.
It is a bounded error to call any subprogram declared in the visible part of Containers.Multiway_Trees when the associated container has been finalized. If the operation takes Container as an in out parameter, then it raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for an empty container, or it raises Constraint_Error or Program_Error.
Erroneous Execution
221/3A Cursor value is invalid if any of the following have occurred since it was created:
- The tree that contains the element it designates has been finalized;
- The tree that contains the element it designates has been used as the Source or Target of a call to Move;
- The tree that contains the element it designates has been used as the Target of a call to Assign or the target of an
assignment_statement; 225/3 - The element it designates has been removed from the tree that previously contained the element.
The result of "=" or Has_Element is unspecified if it is called with an invalid cursor parameter. Execution is erroneous if any other subprogram declared in Containers.Multiway_Trees is called with an invalid cursor parameter.
Execution is erroneous if the tree associated with the result of a call to Reference or Constant_Reference is finalized before the result object returned by the call to Reference or Constant_Reference is finalized.
Implementation Requirements
228/3No storage associated with a multiway tree object shall be lost upon assignment or scope exit.
The execution of an assignment_statement for a tree shall have the effect of copying the elements from the source tree object to the target tree object and changing the node count of the target object to that of the source object.
Implementation Advice
230/3Containers.Multiway_Trees should be implemented similarly to a multiway tree. In particular, if N is the overall number of nodes for a particular tree, then the worst-case time complexity of Element, Parent, First_Child, Last_Child, Next_Sibling, Previous_Sibling, Insert_Child with Count=1, and Delete should be O(log N).
Move should not copy elements, and should minimize copying of internal data structures.
If an exception is propagated from a tree operation, no storage should be lost, nor any elements removed from a tree unless specified by the operation.
Extensions to Ada 2005
Inconsistencies With Ada 2012
Incompatibilities With Ada 2012
Extensions to Ada 2012
Wording Changes from Ada 2012
A.18.11 The Generic Package Containers.Indefinite_Vectors
1/2The language-defined generic package Containers.Indefinite_Vectors provides a private type Vector and a set of operations. It provides the same operations as the package Containers.Vectors (see A.18.2), with the difference that the generic formal Element_Type is indefinite.
Static Semantics
2/3The declaration of the generic library package Containers.Indefinite_Vectors has the same contents and semantics as Containers.Vectors except:
- The generic formal Element_Type is indefinite.
- The procedures with the profiles:
procedure Insert (Container : in out Vector;
Before : in Extended_Index;
Count : in Count_Type := 1);
6/2procedure Insert (Container : in out Vector;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1);
- are omitted.
- The actual Element parameter of access subprogram Process of Update_Element may be constrained even if Element_Type is unconstrained.
- The operations "&", Append, Insert, Prepend, Replace_Element, and To_Vector that have a formal parameter of type Element_Type perform indefinite insertion (see A.18).
- The description of Tampering_With_Elements_Prohibited is replaced by:
Returns True if tampering with elements is prohibited for Container, and False otherwise.
- Tampering_With_Cursors_Prohibited is replaced by Tampering_With_Elements_Prohibited in the postcondition for the operations Reference and Constant_Reference.
- The operations Replace_Element, Reverse_Elements, and Swap, and the nested generic unit Generic_Sorting are omitted from the nested package Stable.
Extensions to Ada 95
Inconsistencies With Ada 2012
allocator would raise Program_Error in these circumstances), and that a program inserted a more nested tagged type (or access discriminant) into a container, and then used that object before its type or discriminant went out of scope. All known implementations are implemented in Ada, so we believe there is no practical incompatibility. As such, we mention this only for completeness.A.18.12 The Generic Package Containers.Indefinite_Doubly_Linked_Lists
1/2The language-defined generic package Containers.Indefinite_Doubly_Linked_Lists provides private types List and Cursor, and a set of operations for each type. It provides the same operations as the package Containers.Doubly_Linked_Lists (see A.18.3), with the difference that the generic formal Element_Type is indefinite.
Static Semantics
2/3The declaration of the generic library package Containers.Indefinite_Doubly_Linked_Lists has the same contents and semantics as Containers.Doubly_Linked_Lists except:
- The generic formal Element_Type is indefinite.
- The procedure with the profile:
procedure Insert (Container : in out List;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1);
- is omitted.
- The actual Element parameter of access subprogram Process of Update_Element may be constrained even if Element_Type is unconstrained.
- The operations Append, Insert, Prepend, and Replace_Element that have a formal parameter of type Element_Type perform indefinite insertion (see A.18).
- The description of Tampering_With_Elements_Prohibited is replaced by:
Returns True if tampering with elements is prohibited for Container, and False otherwise.
- Tampering_With_Cursors_Prohibited is replaced by Tampering_With_Elements_Prohibited in the postcondition for the operations Reference and Constant_Reference.
- The operations Replace_Element and Swap are omitted from the nested package Stable.
Extensions to Ada 95
Inconsistencies With Ada 2012
A.18.13 The Generic Package Containers.Indefinite_Hashed_Maps
1/2The language-defined generic package Containers.Indefinite_Hashed_Maps provides a map with the same operations as the package Containers.Hashed_Maps (see A.18.5), with the difference that the generic formal types Key_Type and Element_Type are indefinite.
Static Semantics
2/3The declaration of the generic library package Containers.Indefinite_Hashed_Maps has the same contents and semantics as Containers.Hashed_Maps except:
- The generic formal Key_Type is indefinite.
- The generic formal Element_Type is indefinite.
- The procedure with the profile:
procedure Insert (Container : in out Map;
Key : in Key_Type;
Position : out Cursor;
Inserted : out Boolean);
- is omitted.
- The actual Element parameter of access subprogram Process of Update_Element may be constrained even if Element_Type is unconstrained.
- The operations Include, Insert, Replace, and Replace_Element that have a formal parameter of type Element_Type perform indefinite insertion (see A.18).
- The description of Tampering_With_Elements_Prohibited is replaced by:
Returns True if tampering with elements is prohibited for Container, and False otherwise.
- Tampering_With_Cursors_Prohibited is replaced by Tampering_With_Elements_Prohibited in the postcondition for the operations Reference and Constant_Reference.
- The operations Replace and Replace_Element are omitted from the nested package Stable.
Extensions to Ada 95
Inconsistencies With Ada 2012
A.18.14 The Generic Package Containers.Indefinite_Ordered_Maps
1/2The language-defined generic package Containers.Indefinite_Ordered_Maps provides a map with the same operations as the package Containers.Ordered_Maps (see A.18.6), with the difference that the generic formal types Key_Type and Element_Type are indefinite.
Static Semantics
2/3The declaration of the generic library package Containers.Indefinite_Ordered_Maps has the same contents and semantics as Containers.Ordered_Maps except:
- The generic formal Key_Type is indefinite.
- The generic formal Element_Type is indefinite.
- The procedure with the profile:
procedure Insert (Container : in out Map;
Key : in Key_Type;
Position : out Cursor;
Inserted : out Boolean);
- is omitted.
- The actual Element parameter of access subprogram Process of Update_Element may be constrained even if Element_Type is unconstrained.
- The operations Include, Insert, Replace, and Replace_Element that have a formal parameter of type Element_Type perform indefinite insertion (see A.18).
- The description of Tampering_With_Elements_Prohibited is replaced by:
Returns True if tampering with elements is prohibited for Container, and False otherwise.
- Tampering_With_Cursors_Prohibited is replaced by Tampering_With_Elements_Prohibited in the postcondition for the operations Reference and Constant_Reference.
- The operations Replace and Replace_Element are omitted from the nested package Stable.
Extensions to Ada 95
Inconsistencies With Ada 2012
A.18.15 The Generic Package Containers.Indefinite_Hashed_Sets
1/2The language-defined generic package Containers.Indefinite_Hashed_Sets provides a set with the same operations as the package Containers.Hashed_Sets (see A.18.8), with the difference that the generic formal type Element_Type is indefinite.
Static Semantics
2/3The declaration of the generic library package Containers.Indefinite_Hashed_Sets has the same contents and semantics as Containers.Hashed_Sets except:
- The generic formal Element_Type is indefinite.
- The actual Element parameter of access subprogram Process of Update_Element_Preserving_Key may be constrained even if Element_Type is unconstrained.
- The operations Include, Insert, Replace, Replace_Element, and To_Set that have a formal parameter of type Element_Type perform indefinite insertion (see A.18).
Extensions to Ada 95
Inconsistencies With Ada 2012
A.18.16 The Generic Package Containers.Indefinite_Ordered_Sets
1/2The language-defined generic package Containers.Indefinite_Ordered_Sets provides a set with the same operations as the package Containers.Ordered_Sets (see A.18.9), with the difference that the generic formal type Element_Type is indefinite.
Static Semantics
2/3The declaration of the generic library package Containers.Indefinite_Ordered_Sets has the same contents and semantics as Containers.Ordered_Sets except:
- The generic formal Element_Type is indefinite.
- The actual Element parameter of access subprogram Process of Update_Element_Preserving_Key may be constrained even if Element_Type is unconstrained.
- The operations Include, Insert, Replace, Replace_Element, and To_Set that have a formal parameter of type Element_Type perform indefinite insertion (see A.18).
Extensions to Ada 95
Inconsistencies With Ada 2012
A.18.17 The Generic Package Containers.Indefinite_Multiway_Trees
1/3The language-defined generic package Containers.Indefinite_Multiway_Trees provides a multiway tree with the same operations as the package Containers.Multiway_Trees (see A.18.10), with the difference that the generic formal Element_Type is indefinite.
Static Semantics
2/3The declaration of the generic library package Containers.Indefinite_Multiway_Trees has the same contents and semantics as Containers.Multiway_Trees except:
- The generic formal Element_Type is indefinite.
- The procedure with the profile:
procedure Insert_Child (Container : in out Tree;
Parent : in Cursor;
Before : in Cursor;
Position : out Cursor;
Count : in Count_Type := 1);
- is omitted.
- The actual Element parameter of access subprogram Process of Update_Element may be constrained even if Element_Type is unconstrained.
- The operations Append_Child, Insert_Child, Prepend_Child, and Replace_Element that have a formal parameter of type Element_Type perform indefinite insertion (see A.18).
- The description of Tampering_With_Elements_Prohibited is replaced by:
Returns True if tampering with elements is prohibited for Container, and False otherwise.
- Tampering_With_Cursors_Prohibited is replaced by Tampering_With_Elements_Prohibited in the postcondition for the operations Reference and Constant_Reference.
- The operations Replace_Element and Swap are omitted from the nested package Stable.
Extensions to Ada 2005
Inconsistencies With Ada 2012
A.18.18 The Generic Package Containers.Indefinite_Holders
1/3The language-defined generic package Containers.Indefinite_Holders provides a private type Holder and a set of operations for that type. A holder container holds a single element of an indefinite type.
A holder container allows the declaration of an object that can be used like an uninitialized variable or component of an indefinite type.
A holder container may be empty. An empty holder does not contain an element.
Static Semantics
4/3The generic library package Containers.Indefinite_Holders has the following declaration:
generic
type Element_Type (<>) is private;
with function "=" (Left, Right : Element_Type) return Boolean is <>;
package Ada.Containers.Indefinite_Holders
with Preelaborate, Remote_Types,
Nonblocking, Global => in out synchronized is
type Holder is tagged private
with Stable_Properties => (Is_Empty,
Tampering_With_The_Element_Prohibited),
Default_Initial_Condition => Is_Empty (Holder),
Preelaborable_Initialization ;
7/3Empty_Holder : constant Holder;
7.1/5function Equal_Element (Left, Right : Element_Type) return Boolean
renames "=";
8/3function "=" (Left, Right : Holder) return Boolean;
8.1/5function Tampering_With_The_Element_Prohibited
(Container : Holder) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
8.2/5function Empty return Holder
is (Empty_Holder)
with Post =>
not Tampering_With_The_Element_Prohibited (Empty'Result)
and then Is_Empty (Empty'Result);
9/5function To_Holder (New_Item : Element_Type) return Holder
with Post => not Is_Empty (To_Holder'Result);
10/5function Is_Empty (Container : Holder) return Boolean
with Global => null, Use_Formal => null;
11/5procedure Clear (Container : in out Holder)
with Pre => not Tampering_With_The_Element_Prohibited (Container)
or else raise Program_Error,
Post => Is_Empty (Container);
12/5function Element (Container : Holder) return Element_Type
with Pre => not Is_Empty (Container) or else raise Constraint_Error,
Global => null, Use_Formal => Element_Type;
13/5procedure Replace_Element (Container : in out Holder;
New_Item : in Element_Type)
with Pre => not Tampering_With_The_Element_Prohibited (Container)
or else raise Program_Error,
Post => not Is_Empty (Container);
14/5procedure Query_Element
(Container : in Holder;
Process : not null access procedure (Element : in Element_Type))
with Pre => not Is_Empty (Container) or else raise Constraint_Error;
15/5procedure Update_Element
(Container : in out Holder;
Process : not null access procedure (Element : in out Element_Type))
with Pre => not Is_Empty (Container) or else raise Constraint_Error;
16/5type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
17/5type Reference_Type
(Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
18/5function Constant_Reference (Container : aliased in Holder)
return Constant_Reference_Type
with Pre => not Is_Empty (Container)
or else raise Constraint_Error,
Post => Tampering_With_The_Element_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
19/5function Reference (Container : aliased in out Holder)
return Reference_Type
with Pre => not Is_Empty (Container)
or else raise Constraint_Error,
Post => Tampering_With_The_Element_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
20/5procedure Assign (Target : in out Holder; Source : in Holder)
with Post => (Is_Empty (Source) = Is_Empty (Target));
21/5function Copy (Source : Holder) return Holder
with Post => (Is_Empty (Source) = Is_Empty (Copy'Result));
22/5procedure Move (Target : in out Holder; Source : in out Holder)
with Pre => (not Tampering_With_The_Element_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_The_Element_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Is_Empty (Source) and then (not Is_Empty (Target)));
22.1/5procedure Swap (Left, Right : in out Holder)
with Pre => (not Tampering_With_The_Element_Prohibited (Left)
or else raise Program_Error) and then
(not Tampering_With_The_Element_Prohibited (Right)
or else raise Program_Error),
Post => Is_Empty (Left) = Is_Empty (Right)'Old and then
Is_Empty (Right) = Is_Empty (Left)'Old;
23/3private
24/3... -- not specified by the language
25/3end Ada.Containers.Indefinite_Holders;
The actual function for the generic formal function "=" on Element_Type values is expected to define a reflexive and symmetric relationship and return the same result value each time it is called with a particular pair of values. If it behaves in some other manner, the function "=" on holder values returns an unspecified value. The exact arguments and number of calls of this generic formal function by the function "=" on holder values are unspecified.
The type Holder is used to represent holder containers. The type Holder needs finalization (see 7.6).
Empty_Holder represents an empty holder object. If an object of type Holder is not otherwise initialized, it is initialized to the same value as Empty_Holder.
[Some operations check for “tampering with the element” of a container because they depend on the element of the container not being replaced.]When tampering with the element is prohibited for a particular holder object H, Program_Error is propagated by the finalization of H[, as well as by a call that passes H to certain of the operations of this package, as indicated by the precondition of such an operation].
Paragraphs 30 through 35 are removed as preconditions now describe these rules.
function "=" (Left, Right : Holder) return Boolean;
If Left and Right denote the same holder object, then the function returns True. Otherwise, it compares the element contained in Left to the element contained in Right using the generic formal equality operator, returning the result of that operation. Any exception raised during the evaluation of element equality is propagated.
function Tampering_With_The_Element_Prohibited
(Container : Holder) return Boolean
with Nonblocking, Global => null, Use_Formal => null;
Returns True if tampering with the element is currently prohibited for Container, and returns False otherwise.
function To_Holder (New_Item : Element_Type) return Holder
with Post => not Is_Empty (To_Holder'Result);
Returns a nonempty holder containing an element initialized to New_Item. To_Holder performs indefinite insertion (see A.18).
function Is_Empty (Container : Holder) return Boolean
with Global => null, Use_Formal => null;
Returns True if Container is empty, and False if it contains an element.
procedure Clear (Container : in out Holder)
with Pre => not Tampering_With_The_Element_Prohibited (Container)
or else raise Program_Error,
Post => Is_Empty (Container);
Removes the element from Container.
function Element (Container : Holder) return Element_Type
with Pre => not Is_Empty (Container) or else raise Constraint_Error,
Global => null, Use_Formal => Element_Type;
Returns the element stored in Container.
procedure Replace_Element (Container : in out Holder;
New_Item : in Element_Type)
with Pre => not Tampering_With_The_Element_Prohibited (Container)
or else raise Program_Error,
Post => not Is_Empty (Container);
Replace_Element assigns the value New_Item into Container, replacing any preexisting content of Container; Replace_Element performs indefinite insertion (see A.18).
procedure Query_Element
(Container : in Holder;
Process : not null access procedure (Element : in Element_Type))
with Pre => not Is_Empty (Container) or else raise Constraint_Error,
Global => null, Use_Formal => null;
Query_Element calls Process.all with the contained element as the argument. Tampering with the element of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
procedure Update_Element
(Container : in out Holder;
Process : not null access procedure (Element : in out Element_Type))
with Pre => not Is_Empty (Container) or else raise Constraint_Error;
Update_Element calls Process.all with the contained element as the argument. Tampering with the element of Container is prohibited during the execution of the call on Process.all. Any exception raised by Process.all is propagated.
type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
53/5type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element,
Nonblocking, Global => in out synchronized,
Default_Initial_Condition => (raise Program_Error);
The types Constant_Reference_Type and Reference_Type need finalization.
This paragraph was deleted.
function Constant_Reference (Container : aliased in Holder)
return Constant_Reference_Type
with Pre => not Is_Empty (Container) or else raise Constraint_Error,
Post => Tampering_With_The_Element_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Implicit_Dereference aspect) provides a convenient way to gain read access to the contained element of a holder container.
Constant_Reference returns an object whose discriminant is an access value that designates the contained element. Tampering with the element of Container is prohibited while the object returned by Constant_Reference exists and has not been finalized.
function Reference (Container : aliased in out Holder)
return Reference_Type
with Pre => not Is_Empty (Container) or else raise Constraint_Error,
Post => Tampering_With_The_Element_Prohibited (Container),
Nonblocking, Global => null, Use_Formal => null;
This function (combined with the Implicit_Dereference aspects) provides a convenient way to gain read and write access to the contained element of a holder container.
Reference returns an object whose discriminant is an access value that designates the contained element. Tampering with the element of Container is prohibited while the object returned by Reference exists and has not been finalized.
procedure Assign (Target : in out Holder; Source : in Holder)
with Post => (Is_Empty (Source) = Is_Empty (Target));
If Target denotes the same object as Source, the operation has no effect. If Source is empty, Clear (Target) is called. Otherwise, Replace_Element (Target, Element (Source)) is called.
function Copy (Source : Holder) return Holder
with Post => (Is_Empty (Source) = Is_Empty (Copy'Result));
If Source is empty, returns an empty holder container; otherwise, returns To_Holder (Element (Source)).
procedure Move (Target : in out Holder; Source : in out Holder)
with Pre => (not Tampering_With_The_Element_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_The_Element_Prohibited (Source)
or else raise Program_Error),
Post => (if not Target'Has_Same_Storage (Source) then
Is_Empty (Source) and then (not Is_Empty (Target)));
If Target denotes the same object as Source, then the operation has no effect. Otherwise, the element contained by Source (if any) is removed from Source and inserted into Target, replacing any preexisting content.
procedure Swap (Left, Right : in out Holder)
with Pre => (not Tampering_With_The_Element_Prohibited (Left)
or else raise Program_Error) and then
(not Tampering_With_The_Element_Prohibited (Right)
or else raise Program_Error),
Post => Is_Empty (Left) = Is_Empty (Right)'Old and then
Is_Empty (Right) = Is_Empty (Left)'Old;
If Left denotes the same object as Right, then the operation has no effect. Otherwise, operation exchanges the elements (if any) contained by Left and Right.
Bounded (Run-Time) Errors
68/3It is a bounded error for the actual function associated with a generic formal subprogram, when called as part of an operation of this package, to tamper with the element of any Holder parameter of the operation. Either Program_Error is raised, or the operation works as defined on the value of the Holder either prior to, or subsequent to, some or all of the modifications to the Holder.
It is a bounded error to call any subprogram declared in the visible part of Containers.Indefinite_Holders when the associated container has been finalized. If the operation takes Container as an in out parameter, then it raises Constraint_Error or Program_Error. Otherwise, the operation either proceeds as it would for an empty container, or it raises Constraint_Error or Program_Error.
Erroneous Execution
70/3Execution is erroneous if the holder container associated with the result of a call to Reference or Constant_Reference is finalized before the result object returned by the call to Reference or Constant_Reference is finalized.
Implementation Requirements
71/3No storage associated with a holder object shall be lost upon assignment or scope exit.
The execution of an assignment_statement for a holder container shall have the effect of copying the element (if any) from the source holder object to the target holder object.
Implementation Advice
73/5Move and Swap should not copy any elements , and should minimize copying of internal data structures.
If an exception is propagated from a holder operation, no storage should be lost, nor should the element be removed from a holder container unless specified by the operation.
Extensions to Ada 2005
Inconsistencies With Ada 2012
Incompatibilities With Ada 2012
Wording Changes from Ada 2012
A.18.19 The Generic Package Containers.Bounded_Vectors
1/3The language-defined generic package Containers.Bounded_Vectors provides a private type Vector and a set of operations. It provides the same operations as the package Containers.Vectors (see A.18.2), with the difference that the maximum storage is bounded.
Static Semantics
2/3The declaration of the generic library package Containers.Bounded_Vectors has the same contents and semantics as Containers.Vectors except:
- The aspect Preelaborate is replaced with aspect Pure. Aspect Global is deleted.
- The type Vector is declared with a discriminant that specifies the capacity:
type Vector (Capacity : Count_Type) is tagged private...
- The
aspect_definitionfor Preelaborable_Initialization for type Vector is changed to:
Preelaborable_Initialization =>
Element_Type'Preelaborable_Initialization
- The type Vector needs finalization if and only if type Element_Type needs finalization.
- Capacity is omitted from the Stable_Properties of type Vector.
- In function Empty, the postcondition is altered to:
Post =>
Empty'Result.Capacity = Capacity and then
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
- In function Copy, the postcondition is altered to:
Post => Length (Copy'Result) = Length (Source) and then
(if Capacity > Length (Source) then
Copy'Result.Capacity = Capacity
else Copy'Result.Capacity >= Length (Source));
- The description of Reserve_Capacity is replaced with:
procedure Reserve_Capacity (Container : in out Vector;
Capacity : in Count_Type)
with Pre => Capacity <= Container.Capacity
or else raise Capacity_Error;
This operation has no effect, [other than checking the precondition].
- The portion of the postcondition checking the capacity is omitted from subprograms Set_Length, Assign, Insert, Insert_Space, Prepend, Append, and Delete.
- For procedures Insert, Insert_Space, Prepend, and Append, the part of the precondition reading:
(<some length> <= Maximum_Length - <some other length>
or else raise Constraint_Error)
- is replaced by:
(<some length> <= Maximum_Length - <some other length>
or else raise Constraint_Error) and then
(<some length> <= Container.Capacity - <some other length>
or else raise Capacity_Error)
Bounded (Run-Time) Errors
10/3It is a bounded error to assign from a bounded vector object while tampering with elements [or cursors] of that object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target object prohibiting tampering with elements [or cursors], or execution proceeds normally.
Erroneous Execution
11/3When a bounded vector object V is finalized, if tampering with cursors is prohibited for V other than due to an assignment from another vector, then execution is erroneous.
Implementation Requirements
12/3For each instance of Containers.Vectors and each instance of Containers.Bounded_Vectors, if the two instances meet the following conditions, then the output generated by the Vector'Output or Vector'Write subprograms of either instance shall be readable by the Vector'Input or Vector'Read of the other instance, respectively:
- the Element_Type parameters of the two instances are statically matching subtypes of the same type; and
- the output generated by Element_Type'Output or Element_Type'Write is readable by Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the type of the two actual Element_Type parameters); and
- the preceding two conditions also hold for the Index_Type parameters of the instances.
Implementation Advice
16/3Bounded vector objects should be implemented without implicit pointers or dynamic allocation.
The implementation advice for procedure Move to minimize copying does not apply.
Extensions to Ada 2005
Inconsistencies With Ada 2012
Incompatibilities With Ada 2012
A.18.20 The Generic Package Containers.Bounded_Doubly_Linked_Lists
1/3The language-defined generic package Containers.Bounded_Doubly_Linked_Lists provides a private type List and a set of operations. It provides the same operations as the package Containers.Doubly_Linked_Lists (see A.18.3), with the difference that the maximum storage is bounded.
Static Semantics
2/3The declaration of the generic library package Containers.Bounded_Doubly_Linked_Lists has the same contents and semantics as Containers.Doubly_Linked_Lists except:
- The aspect Preelaborate is replaced with aspect Pure. Aspect Global is deleted.
- The type List is declared with a discriminant that specifies the capacity (maximum number of elements) as follows:
type List (Capacity : Count_Type) is tagged private...
- The
aspect_definitionfor Preelaborable_Initialization for type List is changed to:
Preelaborable_Initialization =>
Element_Type'Preelaborable_Initialization
- The type List needs finalization if and only if type Element_Type needs finalization.
- The function Empty is replaced by:
function Empty (Capacity : Count_Type := implementation-defined)
return List
with Post =>
Empty'Result.Capacity = Capacity and then
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
- For procedures Insert, Prepend, Append, Merge, and the three-parameter Splice whose parameter Source has type List, the part of the precondition reading:
(<some length> <= Count_Type'Last - <some other length>
or else raise Constraint_Error)
- is replaced by:
(<some length> <= Count_Type'Last - <some other length>
or else raise Constraint_Error) and then
(<some length> <= Container.Capacity - <some other length>
or else raise Capacity_Error)
- In procedure Assign, the precondition is altered to:
Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Length (Source) <= Target.Capacity
or else raise Capacity_Error),
- The function Copy is replaced with:
function Copy (Source : List; Capacity : Count_Type := 0)
return List
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result) and then
Copy'Result.Capacity = (if Capacity = 0 then
Length (Source) else Capacity);
Returns a list whose elements have the same values as the elements of Source .
- This paragraph was deleted.
- In the four-parameter procedure Splice, the precondition is altered to:
Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(not Tampering_With_Cursors_Prohibited (Source)
or else raise Program_Error) and then
(Position /= No_Element
or else raise Constraint_Error) and then
(Has_Element (Source, Position)
or else raise Program_Error) and then
(Before = No_Element or else Has_Element (Target, Before)
or else raise Program_Error) and then
(Target'Has_Same_Storage (Source) or else
Length (Target) /= Count_Type'Last
or else raise Constraint_Error) and then
(Target'Has_Same_Storage (Source) or else
Length (Target) /= Target.Capacity
or else raise Capacity_Error),
Bounded (Run-Time) Errors
14/3It is a bounded error to assign from a bounded list object while tampering with elements [or cursors] of that object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target object prohibiting tampering with elements [or cursors], or execution proceeds normally.
Erroneous Execution
15/3When a bounded list object L is finalized, if tampering with cursors is prohibited for L other than due to an assignment from another list, then execution is erroneous.
Implementation Requirements
16/3For each instance of Containers.Doubly_Linked_Lists and each instance of Containers.Bounded_Doubly_Linked_Lists, if the two instances meet the following conditions, then the output generated by the List'Output or List'Write subprograms of either instance shall be readable by the List'Input or List'Read of the other instance, respectively:
- the Element_Type parameters of the two instances are statically matching subtypes of the same type; and
- the output generated by Element_Type'Output or Element_Type'Write is readable by Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the type of the two actual Element_Type parameters).
Implementation Advice
19/3Bounded list objects should be implemented without implicit pointers or dynamic allocation.
The implementation advice for procedure Move to minimize copying does not apply.
Extensions to Ada 2005
Inconsistencies With Ada 2012
Incompatibilities With Ada 2012
A.18.21 The Generic Package Containers.Bounded_Hashed_Maps
1/3The language-defined generic package Containers.Bounded_Hashed_Maps provides a private type Map and a set of operations. It provides the same operations as the package Containers.Hashed_Maps (see A.18.5), with the difference that the maximum storage is bounded.
Static Semantics
2/3The declaration of the generic library package Containers.Bounded_Hashed_Maps has the same contents and semantics as Containers.Hashed_Maps except:
- The aspect Preelaborate is replaced with aspect Pure. Aspect Global is deleted.
- The type Map is declared with discriminants that specify both the capacity (number of elements) and modulus (number of distinct hash values) of the hash table as follows:
type Map (Capacity : Count_Type;
Modulus : Hash_Type) is tagged private...
- The
aspect_definitionfor Preelaborable_Initialization for type Map is changed to:
Preelaborable_Initialization =>
Element_Type'Preelaborable_Initialization
and
Key_Type'Preelaborable_Initialization
- The type Map needs finalization if and only if type Key_Type or type Element_Type needs finalization.
- In function Empty, the postcondition is altered to:
Post =>
Empty'Result.Capacity = Capacity and then
Empty'Result.Modulus = Default_Modulus (Capacity) and then
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
- The description of Reserve_Capacity is replaced with:
procedure Reserve_Capacity (Container : in out Map;
Capacity : in Count_Type)
with Pre => Capacity <= Container.Capacity
or else raise Capacity_Error;
This operation has no effect, [other than checking the precondition].
- An additional operation is added immediately following Reserve_Capacity:
function Default_Modulus (Capacity : Count_Type) return Hash_Type;
Default_Modulus returns an implementation-defined value for the number of distinct hash values to be used for the given capacity (maximum number of elements).
- For procedures Insert and Include, the part of the precondition reading:
(<some length> <= Count_Type'Last - <some other length>
or else raise Constraint_Error)
- is replaced by:
(<some length> <= Count_Type'Last - <some other length>
or else raise Constraint_Error) and then
(<some length> > Container.Capacity - <some other length>
or else raise Capacity_Error)
- In procedure Assign, the precondition is altered to:
Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Length (Source) <= Target.Capacity
or else raise Capacity_Error),
- The function Copy is replaced with:
function Copy (Source : Map;
Capacity : Count_Type := 0;
Modulus : Hash_Type := 0) return Map
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result) and then
Copy'Result.Capacity = (if Capacity = 0 then
Length (Source) else Capacity) and then
Copy'Result.Modulus = (if Modulus = 0 then
Default_Modulus (Capacity) else Modulus);
Returns a map with key/element pairs initialized from the values in Source.
Bounded (Run-Time) Errors
15/3It is a bounded error to assign from a bounded map object while tampering with elements [or cursors] of that object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target object prohibiting tampering with elements [or cursors], or execution proceeds normally.
Erroneous Execution
16/3When a bounded map object M is finalized, if tampering with cursors is prohibited for M other than due to an assignment from another map, then execution is erroneous.
Implementation Requirements
17/3For each instance of Containers.Hashed_Maps and each instance of Containers.Bounded_Hashed_Maps, if the two instances meet the following conditions, then the output generated by the Map'Output or Map'Write subprograms of either instance shall be readable by the Map'Input or Map'Read of the other instance, respectively:
- the Element_Type parameters of the two instances are statically matching subtypes of the same type; and
- the output generated by Element_Type'Output or Element_Type'Write is readable by Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the type of the two actual Element_Type parameters); and
- the preceding two conditions also hold for the Key_Type parameters of the instances.
Implementation Advice
21/3Bounded hashed map objects should be implemented without implicit pointers or dynamic allocation.
The implementation advice for procedure Move to minimize copying does not apply.
Extensions to Ada 2005
Inconsistencies With Ada 2012
Incompatibilities With Ada 2012
A.18.22 The Generic Package Containers.Bounded_Ordered_Maps
1/3The language-defined generic package Containers.Bounded_Ordered_Maps provides a private type Map and a set of operations. It provides the same operations as the package Containers.Ordered_Maps (see A.18.6), with the difference that the maximum storage is bounded.
Static Semantics
2/3The declaration of the generic library package Containers.Bounded_Ordered_Maps has the same contents and semantics as Containers.Ordered_Maps except:
- The aspect Preelaborate is replaced with aspect Pure. Aspect Global is deleted.
- The type Map is declared with a discriminant that specifies the capacity (maximum number of elements) as follows:
type Map (Capacity : Count_Type) is tagged private...
- The
aspect_definitionfor Preelaborable_Initialization for type Map is changed to:
Preelaborable_Initialization =>
Element_Type'Preelaborable_Initialization
and
Key_Type'Preelaborable_Initialization
- The type Map needs finalization if and only if type Key_Type or type Element_Type needs finalization.
- The function Empty is replaced by:
function Empty (Capacity : Count_Type := implementation-defined)
return Map
with Post =>
Empty'Result.Capacity = Capacity and then
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
- For procedures Insert and Include, the part of the precondition reading:
(<some length> <= Count_Type'Last - <some other length>
or else raise Constraint_Error)
- is replaced by:
(<some length> <= Count_Type'Last - <some other length>
or else raise Constraint_Error) and then
(<some length> <= Container.Capacity - <some other length>
or else raise Capacity_Error)
- In procedure Assign, the precondition is altered to:
Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Length (Source) <= Target.Capacity
or else raise Capacity_Error),
- The function Copy is replaced with:
function Copy (Source : Map;
Capacity : Count_Type := 0) return Map
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result) and then
Copy'Result.Capacity = (if Capacity = 0 then
Length (Source) else Capacity);
Returns a map with key/element pairs initialized from the values in Source.
Bounded (Run-Time) Errors
12/3It is a bounded error to assign from a bounded map object while tampering with elements [or cursors] of that object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target object prohibiting tampering with elements [or cursors], or execution proceeds normally.
Erroneous Execution
13/3When a bounded map object M is finalized, if tampering with cursors is prohibited for M other than due to an assignment from another map, then execution is erroneous.
Implementation Requirements
14/3For each instance of Containers.Ordered_Maps and each instance of Containers.Bounded_Ordered_Maps, if the two instances meet the following conditions, then the output generated by the Map'Output or Map'Write subprograms of either instance shall be readable by the Map'Input or Map'Read of the other instance, respectively:
- the Element_Type parameters of the two instances are statically matching subtypes of the same type; and
- the output generated by Element_Type'Output or Element_Type'Write is readable by Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the type of the two actual Element_Type parameters); and
- the preceding two conditions also hold for the Key_Type parameters of the instances.
Implementation Advice
18/3Bounded ordered map objects should be implemented without implicit pointers or dynamic allocation.
The implementation advice for procedure Move to minimize copying does not apply.
Extensions to Ada 2005
Inconsistencies With Ada 2012
Incompatibilities With Ada 2012
A.18.23 The Generic Package Containers.Bounded_Hashed_Sets
1/3The language-defined generic package Containers.Bounded_Hashed_Sets provides a private type Set and a set of operations. It provides the same operations as the package Containers.Hashed_Sets (see A.18.8), with the difference that the maximum storage is bounded.
Static Semantics
2/3The declaration of the generic library package Containers.Bounded_Hashed_Sets has the same contents and semantics as Containers.Hashed_Sets except:
- The aspect Preelaborate is replaced with aspect Pure. Aspect Global is deleted.
- The type Set is declared with discriminants that specify both the capacity (number of elements) and modulus (number of distinct hash values) of the hash table as follows:
type Set (Capacity : Count_Type;
Modulus : Hash_Type) is tagged private...
- The
aspect_definitionfor Preelaborable_Initialization for type Set is changed to:
Preelaborable_Initialization =>
Element_Type'Preelaborable_Initialization
- The type Set needs finalization if and only if type Element_Type needs finalization.
- In function Empty, the postcondition is altered to:
Post =>
Empty'Result.Capacity = Capacity and then
Empty'Result.Modulus = Default_Modulus (Capacity) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
- The description of Reserve_Capacity is replaced with:
procedure Reserve_Capacity (Container : in out Set;
Capacity : in Count_Type)
with Pre => Capacity <= Container.Capacity
or else raise Capacity_Error;
This operation has no effect, [other than checking the precondition].
- An additional operation is added immediately following Reserve_Capacity:
function Default_Modulus (Capacity : Count_Type) return Hash_Type;
Default_Modulus returns an implementation-defined value for the number of distinct hash values to be used for the given capacity (maximum number of elements).
- For procedures Insert and Include, the part of the precondition reading:
(<some length> <= Count_Type'Last - <some other length>
or else raise Constraint_Error)
- is replaced by:
(<some length> <= Count_Type'Last - <some other length>
or else raise Constraint_Error) and then
(<some length> <= Container.Capacity - <some other length>
or else raise Capacity_Error)
- In procedure Assign, the precondition is altered to:
Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Length (Source) <= Target.Capacity
or else raise Capacity_Error),
- The function Copy is replaced with:
function Copy (Source : Set;
Capacity : Count_Type := 0;
Modulus : Hash_Type := 0) return Map
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Cursors_Prohibited (Copy'Result) and then
Copy'Result.Capacity = (if Capacity = 0 then
Length (Source) else Capacity) and then
Copy'Result.Modulus = (if Modulus = 0 then
Default_Modulus (Capacity) else Modulus);
Returns a set with key/element pairs initialized from the values in Source.
Bounded (Run-Time) Errors
15/3It is a bounded error to assign from a bounded set object while tampering with elements [or cursors] of that object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target object prohibiting tampering with elements [or cursors], or execution proceeds normally.
Erroneous Execution
16/3When a bounded set object S is finalized, if tampering with cursors is prohibited for S other than due to an assignment from another set, then execution is erroneous.
Implementation Requirements
17/3For each instance of Containers.Hashed_Sets and each instance of Containers.Bounded_Hashed_Sets, if the two instances meet the following conditions, then the output generated by the Set'Output or Set'Write subprograms of either instance shall be readable by the Set'Input or Set'Read of the other instance, respectively:
- the Element_Type parameters of the two instances are statically matching subtypes of the same type; and
- the output generated by Element_Type'Output or Element_Type'Write is readable by Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the type of the two actual Element_Type parameters).
Implementation Advice
20/3Bounded hashed set objects should be implemented without implicit pointers or dynamic allocation.
The implementation advice for procedure Move to minimize copying does not apply.
Extensions to Ada 2005
Incompatibilities With Ada 2012
A.18.24 The Generic Package Containers.Bounded_Ordered_Sets
1/3The language-defined generic package Containers.Bounded_Ordered_Sets provides a private type Set and a set of operations. It provides the same operations as the package Containers.Ordered_Sets (see A.18.9), with the difference that the maximum storage is bounded.
Static Semantics
2/3The declaration of the generic library package Containers.Bounded_Ordered_Sets has the same contents and semantics as Containers.Ordered_Sets except:
- The aspect Preelaborate is replaced with aspect Pure. Aspect Global is deleted.
- The type Set is declared with a discriminant that specifies the capacity (maximum number of elements) as follows:
type Set (Capacity : Count_Type) is tagged private...
- The
aspect_definitionfor Preelaborable_Initialization for type Set is changed to:
Preelaborable_Initialization =>
Element_Type'Preelaborable_Initialization
- The type Set needs finalization if and only if type Element_Type needs finalization.
- The function Empty is replaced by:
function Empty (Capacity : Count_Type := implementation-defined)
return Set
with Post =>
Empty'Result.Capacity = Capacity and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Length (Empty'Result) = 0;
- For procedures Insert and Include, the part of the precondition reading:
(<some length> <= Count_Type'Last - <some other length>
or else raise Constraint_Error)
- is replaced by:
(<some length> <= Count_Type'Last - <some other length>
or else raise Constraint_Error) and then
(<some length> <= Container.Capacity - <some other length>
or else raise Capacity_Error)
- In procedure Assign, the precondition is altered to:
Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Length (Source) <= Target.Capacity
or else raise Capacity_Error),
- The function Copy is replaced with:
function Copy (Source : Set;
Capacity : Count_Type := 0) return Map
with Pre => Capacity = 0 or else Capacity >= Length (Source)
or else raise Capacity_Error,
Post =>
Length (Copy'Result) = Length (Source) and then
not Tampering_With_Cursors_Prohibited (Copy'Result) and then
Copy'Result.Capacity = (if Capacity = 0 then
Length (Source) else Capacity);
Returns a set with key/element pairs initialized from the values in Source.
Bounded (Run-Time) Errors
12/3It is a bounded error to assign from a bounded set object while tampering with elements [or cursors] of that object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target object prohibiting tampering with elements [or cursors], or execution proceeds normally.
Erroneous Execution
13/3When a bounded set object S is finalized, if tampering with cursors is prohibited for S other than due to an assignment from another set, then execution is erroneous.
Implementation Requirements
14/3For each instance of Containers.Ordered_Sets and each instance of Containers.Bounded_Ordered_Sets, if the two instances meet the following conditions, then the output generated by the Set'Output or Set'Write subprograms of either instance shall be readable by the Set'Input or Set'Read of the other instance, respectively:
- the Element_Type parameters of the two instances are statically matching subtypes of the same type; and
- the output generated by Element_Type'Output or Element_Type'Write is readable by Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the type of the two actual Element_Type parameters).
Implementation Advice
17/3Bounded ordered set objects should be implemented without implicit pointers or dynamic allocation.
The implementation advice for procedure Move to minimize copying does not apply.
Extensions to Ada 2005
Incompatibilities With Ada 2012
A.18.25 The Generic Package Containers.Bounded_Multiway_Trees
1/3The language-defined generic package Containers.Bounded_Multiway_Trees provides a private type Tree and a set of operations. It provides the same operations as the package Containers.Multiway_Trees (see A.18.10), with the difference that the maximum storage is bounded.
Static Semantics
2/3The declaration of the generic library package Containers.Bounded_Multiway_Trees has the same contents and semantics as Containers.Multiway_Trees except:
- The aspect Preelaborate is replaced with aspect Pure. Aspect Global is deleted.
- The type Tree is declared with a discriminant that specifies the capacity (maximum number of elements) as follows:
type Tree (Capacity : Count_Type) is tagged private...
- The
aspect_definitionfor Preelaborable_Initialization for type Tree is changed to:
Preelaborable_Initialization =>
Element_Type'Preelaborable_Initialization
- The type Tree needs finalization if and only if type Element_Type needs finalization.
- The function Empty is replaced by:
function Empty (Capacity : Count_Type := implementation-defined)
return Tree
with Post =>
Empty'Result.Capacity = Capacity and then
not Tampering_With_Elements_Prohibited (Empty'Result) and then
not Tampering_With_Cursors_Prohibited (Empty'Result) and then
Node_Count (Empty'Result) = 1;
- For procedures Insert_Child, Prepend_Child, and Append_Child, the initial subexpression of the precondition is replaced with:
with Pre => (not Tampering_With_Cursors_Prohibited (Container)
or else raise Program_Error) and then
(Node_Count (Container) - 1 <= Container.Capacity - Count
or else raise Capacity_Error)
- In procedure Assign, the precondition is altered to:
Pre => (not Tampering_With_Cursors_Prohibited (Target)
or else raise Program_Error) and then
(Node_Count (Source) - 1 <= Target.Capacity
or else raise Capacity_Error),
- Function Copy is declared as follows:
function Copy (Source : Tree; Capacity : Count_Type := 0)
return Tree
with Pre => Capacity = 0 or else Capacity >= Node_Count (Source) - 1
or else raise Capacity_Error,
Post =>
Node_Count (Copy'Result) = Node_Count (Source) and then
not Tampering_With_Elements_Prohibited (Copy'Result) and then
not Tampering_With_Cursors_Prohibited (Copy'Result) and then
Copy'Result.Capacity = (if Capacity = 0 then
Node_Count (Source) - 1 else Capacity);
Returns a list whose elements have the same values as the elements of Source.
- In the four-parameter procedure Copy_Subtree, the last or else of the precondition is replaced by:
(not Is_Root (Source)
or else raise Constraint_Error) and then
(Node_Count (Target) - 1 + Subtree_Node_Count (Source) <=
Target.Capacity
or else raise Capacity_Error),
- In the five-parameter procedure Copy_Subtree, the last or else of the precondition is replaced by:
(not Is_Root (Source, Subtree)
or else raise Constraint_Error) and then
(Node_Count (Target) - 1 +
Subtree_Node_Count (Source, Subtree) <= Target.Capacity
or else raise Capacity_Error),
- In Copy_Local_Subtree, the last or else of the precondition is replaced by:
(not Is_Root (Source, Subtree)
or else raise Constraint_Error) and then
(Node_Count (Target) - 1 +
Subtree_Node_Count (Target, Source) <= Target.Capacity
or else raise Capacity_Error),
- In the five-parameter procedure Splice_Subtree, the penultimate or else of the precondition is replaced by:
(Has_Element (Source, Position)
or else raise Program_Error) and then
(Target'Has_Same_Storage (Source) or else
Node_Count (Target) - 1 +
Subtree_Node_Count (Source, Position) <= Target.Capacity
or else raise Capacity_Error) and then
- In the five-parameter procedure Splice_Children, the penultimate elsif of the precondition is replaced by:
(Before = No_Element or else
Parent (Target, Before) /= Target_Parent
or else raise Constraint_Error) and then
(Target'Has_Same_Storage (Source) or else
Node_Count (Target) - 1 +
Child_Count (Source, Source_Parent) <= Target.Capacity
or else raise Capacity_Error) and then
Bounded (Run-Time) Errors
14/3It is a bounded error to assign from a bounded tree object while tampering with elements [or cursors] of that object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target object prohibiting tampering with elements [or cursors], or execution proceeds normally.
Erroneous Execution
15/3When a bounded tree object T is finalized, if tampering with cursors is prohibited for T other than due to an assignment from another tree, then execution is erroneous.
Implementation Requirements
16/3For each instance of Containers.Multiway_Trees and each instance of Containers.Bounded_Multiway_Trees, if the two instances meet the following conditions, then the output generated by the Tree'Output or Tree'Write subprograms of either instance shall be readable by the Tree'Input or Tree'Read of the other instance, respectively:
- the Element_Type parameters of the two instances are statically matching subtypes of the same type; and
- the output generated by Element_Type'Output or Element_Type'Write is readable by Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the type of the two actual Element_Type parameters).
Implementation Advice
19/3Bounded tree objects should be implemented without implicit pointers or dynamic allocation.
The implementation advice for procedure Move to minimize copying does not apply.
Extensions to Ada 2005
Inconsistencies With Ada 2012
Incompatibilities With Ada 2012
A.18.26 Array Sorting
1/3The language-defined generic procedures Containers.Generic_Array_Sort, Containers.Generic_Constrained_Array_Sort, and Containers.Generic_Sort provide sorting on arbitrary array types.
Static Semantics
2/2The generic library procedure Containers.Generic_Array_Sort has the following declaration:
generic
type Index_Type is (<>);
type Element_Type is private;
type Array_Type is array (Index_Type range <>) of Element_Type;
with function "<" (Left, Right : Element_Type)
return Boolean is <>;
procedure Ada.Containers.Generic_Array_Sort (Container : in out Array_Type)
with Pure, Nonblocking, Global => null ;
Reorders the elements of Container such that the elements are sorted smallest first as determined by the generic formal "<" operator provided. Any exception raised during evaluation of "<" is propagated.
The actual function for the generic formal function "<" of Generic_Array_Sort is expected to return the same value each time it is called with a particular pair of element values. It should define a strict weak ordering relationship (see A.18); it should not modify Container. If the actual for "<" behaves in some other manner, the behavior of the instance of Generic_Array_Sort is unspecified. The number of times Generic_Array_Sort calls "<" is unspecified.
The generic library procedure Containers.Generic_Constrained_Array_Sort has the following declaration:
generic
type Index_Type is (<>);
type Element_Type is private;
type Array_Type is array (Index_Type) of Element_Type;
with function "<" (Left, Right : Element_Type)
return Boolean is <>;
procedure Ada.Containers.Generic_Constrained_Array_Sort
(Container : in out Array_Type)
with Pure, Nonblocking, Global => null ;
Reorders the elements of Container such that the elements are sorted smallest first as determined by the generic formal "<" operator provided. Any exception raised during evaluation of "<" is propagated.
The actual function for the generic formal function "<" of Generic_Constrained_Array_Sort is expected to return the same value each time it is called with a particular pair of element values. It should define a strict weak ordering relationship (see A.18); it should not modify Container. If the actual for "<" behaves in some other manner, the behavior of the instance of Generic_Constrained_Array_Sort is unspecified. The number of times Generic_Constrained_Array_Sort calls "<" is unspecified.
The generic library procedure Containers.Generic_Sort has the following declaration:
generic
type Index_Type is (<>);
with function Before (Left, Right : Index_Type) return Boolean;
with procedure Swap (Left, Right : in Index_Type);
procedure Ada.Containers.Generic_Sort
(First, Last : Index_Type'Base)
with Pure, Nonblocking, Global => null ;
Reorders the elements of an indexable structure, over the range First .. Last, such that the elements are sorted in the ordering determined by the generic formal function Before; Before should return True if Left is to be sorted before Right. The generic formal Before compares the elements having the given indices, and the generic formal Swap exchanges the values of the indicated elements. Any exception raised during evaluation of Before or Swap is propagated.
The actual function for the generic formal function Before of Generic_Sort is expected to return the same value each time it is called with index values that identify a particular pair of element values. It should define a strict weak ordering relationship (see A.18); it should not modify the elements. The actual function for the generic formal Swap should exchange the values of the indicated elements. If the actual for either Before or Swap behaves in some other manner, the behavior of Generic_Sort is unspecified. The number of times the Generic_Sort calls Before or Swap is unspecified.
Implementation Advice
10/2The worst-case time complexity of a call on an instance of Containers.Generic_Array_Sort or Containers.Generic_Constrained_Array_Sort should be O(N**2) or better, and the average time complexity should be better than O(N**2), where N is the length of the Container parameter.
Containers.Generic_Array_Sort and Containers.Generic_Constrained_Array_Sort should minimize copying of elements.
The worst-case time complexity of a call on an instance of Containers.Generic_Sort should be O(N**2) or better, and the average time complexity should be better than O(N**2), where N is the difference between the Last and First parameters plus 1.
Containers.Generic_Sort should minimize calls to the generic formal Swap.
Extensions to Ada 95
Extensions to Ada 2005
Wording Changes from Ada 2005
Wording Changes from Ada 2012
A.18.27 The Generic Package Containers.Synchronized_Queue_Interfaces
1/3The language-defined generic package Containers.Synchronized_Queue_Interfaces provides interface type Queue, and a set of operations for that type. Interface Queue specifies a first-in, first-out queue.
Static Semantics
2/3The generic library package Containers.Synchronized_Queue_Interfaces has the following declaration:
generic
type Element_Type is private;
package Ada.Containers.Synchronized_Queue_Interfaces
with Pure, Nonblocking, Global => null is
type Queue is synchronized interface;
5/5procedure Enqueue
(Container : in out Queue;
New_Item : in Element_Type) is abstract
with Synchronization => By_Entry,
Nonblocking => False,
Global'Class=> in out synchronized;
6/5procedure Dequeue
(Container : in out Queue;
Element : out Element_Type) is abstract
with Synchronization => By_Entry,
Nonblocking => False,
Global'Class=> in out synchronized;
7/5function Current_Use (Container : Queue) return Count_Type is abstract
with Nonblocking, Global'Class => null, Use_Formal => null;
function Peak_Use (Container : Queue) return Count_Type is abstract
with Nonblocking, Global'Class => null, Use_Formal => null,
Post'Class => Peak_Use'Result >= Current_Use (Container);
8/3end Ada.Containers.Synchronized_Queue_Interfaces;
The subprogram behavior descriptions given below are the semantics for the corresponding callable entities found in the language-defined generic packages that have a formal package named Queue_Interfaces.
procedure Enqueue
(Container : in out Queue;
New_Item : in Element_Type) is abstract
with Synchronization => By_Entry
Nonblocking => False,
Global'Class=> in out synchronized;
A queue type that implements this interface is allowed to have a bounded capacity. If the queue object has a bounded capacity, and the number of existing elements equals the capacity, then Enqueue blocks until storage becomes available; otherwise, Enqueue does not block. In any case, it then copies New_Item onto the queue.
procedure Dequeue
(Container : in out Queue;
Element : out Element_Type) is abstract
with Synchronization => By_Entry
Nonblocking => False,
Global'Class=> in out synchronized;
If the queue is empty, then Dequeue blocks until an item becomes available. In any case, it then assigns the element at the head of the queue to Element, and removes it from the queue.
function Current_Use (Container : Queue) return Count_Type is abstract
with Nonblocking, Global'Class=> null, Use_Formal => null;
Returns the number of elements currently in the queue.
function Peak_Use (Container : Queue) return Count_Type is abstract
with Nonblocking, Global'Class=> null, Use_Formal => null,
Post'Class => Peak_Use'Result >= Current_Use (Container);
Returns the maximum number of elements that have been in the queue at any one time.
Extensions to Ada 2005
A.18.28 The Generic Package Containers.Unbounded_Synchronized_Queues
Static Semantics
1/3The language-defined generic package Containers.Unbounded_Synchronized_Queues provides type Queue, which implements the interface type Containers.Synchronized_Queue_Interfaces.Queue.
with System;
with Ada.Containers.Synchronized_Queue_Interfaces;
generic
with package Queue_Interfaces is
new Ada.Containers.Synchronized_Queue_Interfaces (<>);
Default_Ceiling : System.Any_Priority := System.Priority'Last;
package Ada.Containers.Unbounded_Synchronized_Queues
with Preelaborate,
Nonblocking, Global => in out synchronized is
package Implementation is
... -- not specified by the language
end Implementation;
4/3protected type Queue
(Ceiling : System.Any_Priority := Default_Ceiling)
with Priority => Ceiling is
new Queue_Interfaces.Queue with
5/3overriding
entry Enqueue (New_Item : in Queue_Interfaces.Element_Type);
overriding
entry Dequeue (Element : out Queue_Interfaces.Element_Type);
6/5overriding
function Current_Use return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
overriding
function Peak_Use return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
7/3private
... -- not specified by the language
end Queue;
8/3private
9/3... -- not specified by the language
10/3end Ada.Containers.Unbounded_Synchronized_Queues;
The type Queue is used to represent task-safe queues.
The capacity for instances of type Queue is unbounded.
Extensions to Ada 2005
A.18.29 The Generic Package Containers.Bounded_Synchronized_Queues
Static Semantics
1/3The language-defined generic package Containers.Bounded_Synchronized_Queues provides type Queue, which implements the interface type Containers.Synchronized_Queue_Interfaces.Queue.
with System;
with Ada.Containers.Synchronized_Queue_Interfaces;
generic
with package Queue_Interfaces is
new Ada.Containers.Synchronized_Queue_Interfaces (<>);
Default_Capacity : Count_Type;
Default_Ceiling : System.Any_Priority := System.Priority'Last;
package Ada.Containers.Bounded_Synchronized_Queues
with Preelaborate,
Nonblocking, Global => in out synchronized is
package Implementation is
... -- not specified by the language
end Implementation;
4/3protected type Queue
(Capacity : Count_Type := Default_Capacity;
Ceiling : System.Any_Priority := Default_Ceiling)
with Priority => Ceiling is
new Queue_Interfaces.Queue with
5/3overriding
entry Enqueue (New_Item : in Queue_Interfaces.Element_Type);
overriding
entry Dequeue (Element : out Queue_Interfaces.Element_Type);
6/5overriding
function Current_Use return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
overriding
function Peak_Use return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
7/3private
... -- not specified by the language
end Queue;
8/3private
9/3... -- not specified by the language
10/3end Ada.Containers.Bounded_Synchronized_Queues;
The semantics are the same as for Unbounded_Synchronized_Queues, except:
- The capacity for instances of type Queue is bounded and specified by the discriminant Capacity.
Implementation Advice
13/3Bounded queue objects should be implemented without implicit pointers or dynamic allocation.
Extensions to Ada 2005
A.18.30 The Generic Package Containers.Unbounded_Priority_Queues
Static Semantics
1/3The language-defined generic package Containers.Unbounded_Priority_Queues provides type Queue, which implements the interface type Containers.Synchronized_Queue_Interfaces.Queue.
with System;
with Ada.Containers.Synchronized_Queue_Interfaces;
generic
with package Queue_Interfaces is
new Ada.Containers.Synchronized_Queue_Interfaces (<>);
type Queue_Priority is private;
with function Get_Priority
(Element : Queue_Interfaces.Element_Type) return Queue_Priority is <>;
with function Before
(Left, Right : Queue_Priority) return Boolean is <>;
Default_Ceiling : System.Any_Priority := System.Priority'Last;
package Ada.Containers.Unbounded_Priority_Queues
with Preelaborate,
Nonblocking, Global => in out synchronized is
package Implementation is
... -- not specified by the language
end Implementation;
4/3protected type Queue
(Ceiling : System.Any_Priority := Default_Ceiling)
with Priority => Ceiling is
new Queue_Interfaces.Queue with
5/3overriding
entry Enqueue (New_Item : in Queue_Interfaces.Element_Type);
overriding
entry Dequeue (Element : out Queue_Interfaces.Element_Type);
6/3not overriding
procedure Dequeue_Only_High_Priority
(At_Least : in Queue_Priority;
Element : in out Queue_Interfaces.Element_Type;
Success : out Boolean);
7/5overriding
function Current_Use return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
overriding
function Peak_Use return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
8/3private
... -- not specified by the language
end Queue;
9/3private
10/3... -- not specified by the language
11/3end Ada.Containers.Unbounded_Priority_Queues;
The type Queue is used to represent task-safe priority queues.
The capacity for instances of type Queue is unbounded.
Two elements E1 and E2 are equivalent if Before(Get_Priority(E1), Get_Priority(E2)) and Before(Get_Priority(E2), Get_Priority(E1)) both return False.
The actual functions for Get_Priority and Before are expected to return the same value each time they are called with the same actuals, and should not modify their actuals. Before should define a strict weak ordering relationship (see A.18). If the actual functions behave in some other manner, the behavior of Unbounded_Priority_Queues is unspecified.
Enqueue inserts an item according to the order specified by the Before function on the result of Get_Priority on the elements; Before should return True if Left is to be inserted before Right. If the queue already contains elements equivalent to New_Item, then it is inserted after the existing equivalent elements.
For a call on Dequeue_Only_High_Priority, if the head of the nonempty queue is E, and the function Before(At_Least, Get_Priority(E)) returns False, then E is assigned to Element and then removed from the queue, and Success is set to True; otherwise, Success is set to False and Element is unchanged.
Extensions to Ada 2005
A.18.31 The Generic Package Containers.Bounded_Priority_Queues
Static Semantics
1/3The language-defined generic package Containers.Bounded_Priority_Queues provides type Queue, which implements the interface type Containers.Synchronized_Queue_Interfaces.Queue.
with System;
with Ada.Containers.Synchronized_Queue_Interfaces;
generic
with package Queue_Interfaces is
new Ada.Containers.Synchronized_Queue_Interfaces (<>);
type Queue_Priority is private;
with function Get_Priority
(Element : Queue_Interfaces.Element_Type) return Queue_Priority is <>;
with function Before
(Left, Right : Queue_Priority) return Boolean is <>;
Default_Capacity : Count_Type;
Default_Ceiling : System.Any_Priority := System.Priority'Last;
package Ada.Containers.Bounded_Priority_Queues
with Preelaborate,
Nonblocking, Global => in out synchronized is
package Implementation is
... -- not specified by the language
end Implementation;
4/3protected type Queue
(Capacity : Count_Type := Default_Capacity;
Ceiling : System.Any_Priority := Default_Ceiling)
with Priority => Ceiling is
new Queue_Interfaces.Queue with
5/3overriding
entry Enqueue (New_Item : in Queue_Interfaces.Element_Type);
overriding
entry Dequeue (Element : out Queue_Interfaces.Element_Type);
6/3not overriding
procedure Dequeue_Only_High_Priority
(At_Least : in Queue_Priority;
Element : in out Queue_Interfaces.Element_Type;
Success : out Boolean);
7/5overriding
function Current_Use return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
overriding
function Peak_Use return Count_Type
with Nonblocking, Global => null, Use_Formal => null;
8/3private
... -- not specified by the language
end Queue;
9/3private
10/3... -- not specified by the language
11/3end Ada.Containers.Bounded_Priority_Queues;
The semantics are the same as for Unbounded_Priority_Queues, except:
- The capacity for instances of type Queue is bounded and specified by the discriminant Capacity.
Implementation Advice
14/3Bounded priority queue objects should be implemented without implicit pointers or dynamic allocation.
Extensions to Ada 2005
A.18.32 The Generic Package Containers.Bounded_Indefinite_Holders
1/5The language-defined generic package Containers.Bounded_Indefinite_Holders provides a private type Holder and a set of operations for that type. It provides the same operations as the package Containers.Indefinite_Holders (see A.18.18), with the difference that the maximum storage is bounded.
Static Semantics
2/5The declaration of the generic library package Containers.Bounded_Indefinite_Holders has the same contents and semantics as Containers.Indefinite_Holders except:
- The following is added to the context clause:
with System.Storage_Elements; use System.Storage_Elements;
- An additional generic parameter follows Element_Type:
Max_Element_Size_in_Storage_Elements : Storage_Count;
- The
aspect_definitionfor Preelaborable_Initialization for type Holder is changed to:
Preelaborable_Initialization =>
Element_Type'Preelaborable_Initialization
- Add to the precondition of To_Holder and Replace_Element:
and then (New_Item'Size <=
Max_Element_Size_in_Storage_Elements * System.Storage_Unit
or else raise Program_Error)
Bounded (Run-Time) Errors
11/5It is a bounded error to assign from a bounded holder object while tampering with elements of that object is prohibited. Either Program_Error is raised by the assignment, execution proceeds with the target object prohibiting tampering with elements, or execution proceeds normally.
Implementation Requirements
12/5For each instance of Containers.Indefinite_Holders and each instance of Containers.Bounded_Indefinite_Holders, if the two instances meet the following conditions, then the output generated by the Holder'Output or Holder'Write subprograms of either instance shall be readable by the Holder'Input or Holder'Read of the other instance, respectively:
- the Element_Type parameters of the two instances are statically matching subtypes of the same type; and
- the output generated by Element_Type'Output or Element_Type'Write is readable by Element_Type'Input or Element_Type'Read, respectively (where Element_Type denotes the type of the two actual Element_Type parameters).
Implementation Advice
15/5Bounded holder objects should be implemented without dynamic allocation and any finalization should be trivial unless Element_Type needs finalization.
The about the Move and Swap operations is deleted for bounded holders; these operations can copy elements as necessary.
Extensions to Ada 2012
A.18.33 Example of Container Use
Examples
1/3The following example is an implementation of Dijkstra's shortest path algorithm in a directed graph with positive distances. The graph is represented by a map from nodes to sets of edges.
with Ada.Containers.Vectors;
with Ada.Containers.Doubly_Linked_Lists;
use Ada.Containers;
generic
type Node is range <>;
package Shortest_Paths is
type Distance is new Float range 0.0 .. Float'Last;
type Edge is record
To, From : Node;
Length : Distance;
end record;
3/3package Node_Maps is new Vectors (Node, Node);
-- The algorithm builds a map to indicate the node used to reach a given
-- node in the shortest distance.
4/3package Adjacency_Lists is new Doubly_Linked_Lists (Edge);
use Adjacency_Lists;
5/3package Graphs is new Vectors (Node, Adjacency_Lists.List);
6/3package Paths is new Doubly_Linked_Lists (Node);
7/3function Shortest_Path
(G : Graphs.Vector; Source : Node; Target : Node) return Paths.List
with Pre => G (Source) /= Adjacency_Lists.Empty_List;
8/3end Shortest_Paths;
9/5package body Shortest_Paths is
function Shortest_Path
(G : Graphs.Vector; Source : Node; Target : Node) return Paths.List
is
use Node_Maps, Paths, Graphs;
Reached : array (Node) of Boolean := (others => False);
-- The set of nodes whose shortest distance to the source is known.
10/3Reached_From : array (Node) of Node;
So_Far : array (Node) of Distance := (others => Distance'Last);
The_Path : Paths.List := Paths.Empty_List;
Nearest_Distance : Distance;
Next : Node;
begin
So_Far(Source) := 0.0;
11/3while not Reached(Target) loop
Nearest_Distance := Distance'Last;
12/3-- Find closest node not reached yet, by iterating over all nodes.
-- A more efficient algorithm uses a priority queue for this step.
13/3Next := Source;
for N in Node'First .. Node'Last loop
if not Reached(N)
and then So_Far(N) < Nearest_Distance then
Next := N;
Nearest_Distance := So_Far(N);
end if;
end loop;
14/3if Nearest_Distance = Distance'Last then
-- No next node found, graph is not connected
return Paths.Empty_List;
15/3else
Reached(Next) := True;
end if;
16/3-- Update minimum distance to newly reachable nodes.
17/3for E of G (Next) loop
if not Reached(E.To) then
Nearest_Distance := E.Length + So_Far(Next);
18/3if Nearest_Distance < So_Far(E.To) then
Reached_From(E.To) := Next;
So_Far(E.To) := Nearest_Distance;
end if;
end if;
end loop;
end loop;
19/3-- Rebuild path from target to source.
20/5declare
N : Node := Target;
begin
Prepend (The_Path, N);
while N /= Source loop
N := Reached_From(N);
Prepend (The_Path, N);
end loop;
end;
21/3return The_Path;
end;
end Shortest_Paths;
Note that the effect of the Constant_Indexing aspect (on type Vector) and the Implicit_Dereference aspect (on type Reference_Type) is that
G (Next)
is a convenient shorthand for
G.Constant_Reference (Next).Element.all
Similarly, the effect of the loop:
for E of G (Next) loop
if not Reached(E.To) then
...
end if;
end loop;
is the same as:
for C in G (Next).Iterate loop
declare
E : Edge renames G (Next)(C);
begin
if not Reached(E.To) then
...
end if;
end;
end loop;
which is the same as:
declare
L : Adjacency_Lists.List renames G (Next);
C : Adjacency_Lists.Cursor := L.First;
begin
while Has_Element (C) loop
declare
E : Edge renames L(C);
begin
if not Reached(E.To) then
...
end if;
end;
C := L.Next (C);
end loop;
end;